Long-span roofing structures for civil and industrial buildings

Saint Petersburg

building covering beam dome

Introduction

Historical reference

Classification

Planar long-span coating structures

Spatial long-span coating structures

1 Folds

3 Shells

Hanging (cable-stayed) structures

1 Hanging covers

4 Combined systems

Transformable and pneumatic coverings

1 Transformable coverings

Used Books

Introduction

When designing and constructing buildings with indoor spaces, a complex of complex architectural and engineering problems arise. To create comfortable conditions in the hall, meet the requirements of technology, acoustics, and isolate it from other rooms and the environment, the design of the hall covering is of decisive importance. Knowledge of the mathematical laws of shape formation made it possible to make complex geometric constructions (parabolas, hyperbolas, etc.), using the principle of an arbitrary plan.

In modern architecture, the formation of a plan is the result of the development of two trends: a free plan, leading to a structural frame system, and a free plan, requiring a structural system that allows organizing the entire volume of the building, and not just the planning structure.

The hall is the main compositional core of the majority public buildings. The most common plan configurations are rectangle, circle, square, ellipsoidal and horseshoe-shaped plans, less often trapezoidal. When choosing hall covering designs, the need to connect the hall with the outside world through open glazed surfaces or, conversely, to completely isolate it is crucial.

The space, freed from supports and covered with a long-span structure, gives the building emotional and plastic expressiveness.

1. Historical background

Long-span roofing structures appeared in ancient times. These were stone domes and vaults, wooden rafters. For example, the stone dome of the Pantheon in Rome (1125) had a diameter of about 44 m, the dome of the Hagia Sophia Mosque in Istanbul (537) - 32 m, the dome of the Florence Cathedral (1436) - 42 m, the dome Upper Council in the Kremlin (1787) - 22.5 m.

The construction technology of that time did not allow the construction of light structures in stone. Therefore, long-span stone structures were very massive, and the structures themselves were erected over many decades.

Wooden building structures were cheaper and easier to construct than stone ones, and also made it possible to cover large spans. An example is the wooden roof structures of the former Manege building in Moscow (1812), with a span of 30 m.

Development of ferrous metallurgy in the XVIII - XIX centuries. gave builders materials stronger than stone, wood - cast iron and steel.

In the second half of the 19th century. Long-span metal structures are widely used.

At the end of the 18th century. A new material has appeared for long-span buildings - reinforced concrete. Improvement of reinforced concrete structures in the 20th century. led to the emergence of thin-walled spatial structures: shells, folds, domes. A theory of calculation and design of thin-walled coatings has emerged, in which domestic scientists also took part.

In the second half of the 20th century. Suspended coverings, as well as pneumatic and rod systems, are widely used.

The use of long-span structures makes it possible to make maximum use of the load-bearing qualities of the material and thereby obtain lightweight and economical coatings. Reducing the weight of structures and structures is one of the main trends in construction. Reducing mass means reducing the volume of material, its extraction, processing, transportation and installation. Therefore, it is quite natural that builders and architects are interested in new forms of structures, which have a particularly great effect in coatings.

2. Classification

Long-span pavement structures can be divided according to their static operation into two main groups of long-span pavement systems:

· planar (beams, trusses, frames, arches);

· spatial (shells, folds, hanging systems, cross-rod systems, etc.).

Beam, frame and arched, flat systems of long-span coverings are usually designed without taking into account the joint work of all load-bearing elements, since individual flat disks are connected to each other by relatively weak connections that are not capable of significantly distributing the loads. This circumstance naturally leads to an increase in the mass of structures.

To redistribute loads and reduce the mass of spatial structures, connections are required.

According to the material used for the manufacture of long-span structures, they are divided into:

wooden

metal

·reinforced concrete

Ø The wood has good load-bearing properties (the calculated resistance of pine to compression and bending is 130-150 kg/m 2) and low volumetric mass (for air-dried pine 500 kg/m3 ).

There is an opinion that wooden structures are short-lived. Valid at poor care wooden structures can very quickly fail due to damage to the wood by various fungi and insects. The basic rule for preserving wooden structures is to create conditions for their ventilation or airing. It is also important to ensure that the wood is dried before using it in construction. Currently, the woodworking industry can provide effective drying using modern methods, including high-frequency currents, etc.

Improving the biological resistance of wood is easily achieved using long-developed and mastered methods of impregnating it with various effective antiseptics.

Even more often, objections to the use of wood arise for reasons of fire safety.

However, compliance with basic fire safety rules and supervision of structures, as well as the use of fire retardants that increase the fire resistance of wood, can significantly increase the fire-fighting properties of wood.

As an example of the durability of wooden structures, one can cite the already mentioned Manezh in Moscow, which is more than 180 years old, the spire in the Admiralty in Leningrad with a height of about 72 m, built in 1738, the watchtower in Yakutsk, built about 300 years ago, many wooden churches in Vladimir, Suzdal, Kizhi and other cities and villages of Northern Russia, dating back several centuries.

Ø Metal structures, mainly steel, are widely used.

Their advantages: high strength, relatively low weight. The disadvantage of steel structures is susceptibility to corrosion and low fire resistance (loss of load-bearing capacity at high temperatures). There are many means to combat corrosion of steel structures: painting, coating with polymer films, etc. For fire safety purposes, critical steel structures can be concreted or heat-resistant concrete mixtures (vermiculite, etc.) can be sprayed onto the surface of steel structures.

Ø Reinforced concrete structures are not subject to rotting, rusting, and have high fire resistance, but they are heavy.

Therefore, when choosing a material for long-span structures, it is necessary to give preference to the material that, under specific construction conditions, best meets the task.

3. Planar long-span coating structures

In public buildings of mass construction, predominantly traditional flat structures are used to cover indoor spaces: decks, beams, trusses, frames, arches. The operation of these structures is based on the use of internal physical and mechanical properties material and transfer of forces in the body of the structure directly to the supports. In construction, the planar type of coatings has been well studied and mastered in production. Many of them with a span of up to 36 m are designed as prefabricated standard structures. There is constant work to improve them, reduce weight and material consumption.

The flat structure of the hall covering in the interiors of public buildings is almost always, due to its low aesthetic qualities, covered with an expensive suspended ceiling. This creates excess spaces and volumes in the building in the area of ​​the roof structure, which in rare cases are used for technological equipment. In the exterior of a building, such structures, due to their inexpressiveness, are usually hidden behind high parapet walls.

Beams are made of steel profiles, reinforced concrete (prefabricated and monolithic), wooden (glued or nailed).

Steel beams of T-section or box section (Fig. 1, a, b) require a large consumption of metal, have a large deflection, which is usually compensated by the construction lift (1/40-1/50 of the span).

An example is the indoor artificial skating rink in Geneva, built in 1958 (Fig. 1, c). Hall covering dimensions 80.4 × 93.6 m is made of ten integrally welded solid steel beams of variable cross-section, installed every 10.4 m. By installing a console with a guy at one end of the beam, a pre-tension is created, which helps reduce the cross-section of the beam.

Reinforced concrete beams have a large bending moment and a large dead weight, but are easy to manufacture. They can be made monolithic, prefabricated monolithic and prefabricated (from separate blocks and solid). They are made of reinforced concrete with prestressing reinforcement. The ratio of beam height to span ranges from 1/8 to 1/20. In construction practice, there are beams with a span of up to 60 m, and with consoles - up to 100 m. The cross-section of the beams is in the form of a T-beam, I-beam or box-shaped (Fig. 2, a, b, c, d, e, g).

a - steel beam of I-section (composite);

b - box-section steel beam (composite);

c - artificial indoor skating rink in Geneva (1958). The covering measures 80.4 × 93.6 m.

The main beams of I-section are located every 10.4 m.

Aluminum purlins are laid along the main beams.

Rice. 1 (continued)

d - diagrams of unified horizontal trusses

with parallel belts. Developed by TsNIIEP spectacular and

sports facilities;

d - diagrams of gable steel trusses: polygonal and triangular

g - congress hall in Essen (Germany). Coverage dimensions 80.4 × 72.0.

The covering rests on 4 lattice posts. The main trusses have a span of 72.01 m, the secondary ones - 80.4 m with a pitch of 12 m

Rice. 2. Reinforced concrete beams and trusses

a - reinforced concrete single-pitch beam with parallel chords

T-section;

b - reinforced concrete gable beam of I-section;

c - horizontal reinforced concrete beam with parallel chords

I-section;

g - composite reinforced concrete horizontal beam with parallel and

T-section belts;

d - reinforced concrete horizontal beam of box section

Rice. 2 (continued)

e - composite gable reinforced concrete truss, consisting of

two half-trusses with a pre-stressed bottom chord;

g - the building of the British Overseas Aviation Company (BOAC) in London 1955. The reinforced concrete beam has a height of 5.45 m, the cross-section of the beam is rectangular;

z - gymnasium of a high school in Springfield (USA)

In the practice of mass construction in our country, the beams shown in Fig. are widely used. 2, a, b, c.

Wooden beams are used in areas rich in forests. They are typically used in Class III buildings due to their low fire resistance and durability.

Wooden beams are divided into nailed and glued beams up to 30-20 m long. Nail beams (Fig. 3, a) have a wall sewn on nails from two layers of boards, inclined in different directions at an angle of 45°. The upper and lower chords are formed by longitudinal and transverse beams sewn on both sides of the vertical walls. The height of the nail beams is 1/6-1/8 of the beam span. Instead of a plank wall, you can use a wall made of multilayer plywood.

Glued beams, unlike nail beams, have high strength and increased fire resistance even without special impregnation. The cross-section of laminated wooden beams can be rectangular, I-beam, or box-shaped. They are made from slats or boards with glue, laid flat or on edge.

The height of such beams is 1/10-1/12 of the span. According to the outline of the upper and lower chords, laminated beams can be with horizontal chords, single- or double-slope, curved (Fig. 3, b).

Rice. 3 (continued)

Trusses, like beams, can be made of metal, reinforced concrete and wood. Steel trusses, unlike metal beams, require less metal due to their lattice structure. With a suspended ceiling, a walk-through attic is created, allowing passage of utilities or free passage through the attic. Trusses are usually made from steel profiles, and spatial triangular trusses are made from steel pipes.

The Congress and Sports Hall in Essen has a covering size of 80.4 × 72 m (Fig. 1, g). The covering rests on four lattice pillars consisting of four branches. One of the racks is rigidly fixed to the foundation, two racks have roller bearings, the fourth rack is made swinging and can move in two directions. The two main polygonal riveted trusses rest on support posts and have a span of 72 m and a height of 5.94 and 6.63 m in the middle of the span and, respectively, 2.40 and 2.54 m at the supports. The chords of the main trusses have a box section with a width of more than 600 mm, the braces are composite, I-section. Double-cantilever, welded secondary trusses with a span of 80.4 m rest on the main trusses with a pitch of 12 m. The upper chord of these trusses has a cross-section in the form of a T-beam, the lower - in the form of an I-beam with wide flanges. To ensure free vertical deformations at a distance of 11 m from the edges of the roof, through hinges are installed both in the enclosing structure of the covering, and in the trusses and in the suspended ceiling. The ends of the 11 m long trusses rest on light swinging posts located in the stands. Cross wind horizontal ties are located between the main and between the outermost secondary trusses, as well as along the longitudinal walls at a distance of 3.5 m from the edge of the covering. The purlins and sheathing are made of I-beams. The building is covered with 48 mm thick compressed straw slabs, on which a waterproofing carpet of four layers of hot bitumen on fiberglass is laid.

Trusses can have different outlines of both the upper and lower chords. The most common trusses are triangular and polygonal, as well as horizontal ones with parallel belts (Fig. 1, d, e, g).

Reinforced concrete trusses are manufactured: solid - up to 30 m long; composite - with prestressing reinforcement, with a length of more than 30 m. The ratio of the height of the truss to the span is 1/6-1/9.

The lower belt is usually horizontal, the upper belt can have a horizontal, triangular, segment or polygonal outline. The most widespread are reinforced concrete polygonal (gable) trusses, shown in Fig. 2, f. The maximum length of the designed reinforced concrete trusses is about 100 m at a pitch of 12 m.

The disadvantage of reinforced concrete trusses is their large structural height. To reduce the dead weight of trusses, it is necessary to use high-strength concrete and introduce lightweight covering slabs made of efficient materials.

Wooden trusses - can be presented in the form of log or timber hanging rafters. Wooden trusses are used for spans of more than 18 m and subject to preventive fire safety measures. The upper (compressed) chord and braces of wooden trusses are made from square or rectangular beams with a side equal to 1/50-1/80 of the span, the lower (stretched) chord and suspensions are made from both beams and steel strands with screw threads at the ends to tension them using nuts with washers.

The stability of wooden trusses is ensured by wooden braces and ties installed along the edges and in the middle of the truss perpendicular to their plane, as well as roofing decks that form a hard disk of the covering. In domestic construction practice, trusses with a span of 15, 18, 21 and 24 m are used, the upper chord of which is made from a continuous package of boards 170 mm wide using FR-12 glue. The braces are made of bars of the same width, the lower belt is made of rolled angles, and the suspension is made of round steel (Figure 3, c).

Metal-wood trusses - were developed by TsNIIEP educational buildings, TsNIIEP entertainment buildings and sports facilities and TsNIISK Gosstroy of the USSR in 1973. These trusses are installed at intervals of 3 and 6 m and can be used for roofing in two versions:

a) with a warm exploitable suspended ceiling and cold roofing panels;

b) without a suspended ceiling and warm roofing panels.

Frames are planar spacer structures. Unlike a non-thrust beam-post structure, the crossbar and the post in the frame structure have a rigid connection, which causes bending moments to appear in the post due to the impact of loads on the frame crossbar.

Frame structures are made with rigid embedding of supports into the foundation, if there is no danger of uneven settlement of the foundation. The special sensitivity of frame and arched structures to uneven settlements leads to the need for hinged frames (two-hinged and three-hinged). Schemes of arches in Fig. 4, a, b, c, d.

Considering that the frames do not have sufficient rigidity in their plane, when constructing the covering it is necessary to ensure the longitudinal rigidity of the entire covering by embedding the covering elements or installing diaphragm frames normal to the plane, or stiffening links.

Frames can be made of metal, reinforced concrete or wood.

Metal frames can be made of either solid or lattice sections. The lattice section is typical for frames with large spans, as it is more economical due to its low dead weight and the ability to withstand both compressive and tensile forces equally well. The cross-sectional height of the cross-sections of lattice frames is taken to be within 1/20-1/25 of the span, and of solid-section frames 1/25-/30 of the span. To reduce the height of the cross-section of the cross-section of both solid and lattice metal frames, unloading consoles are used, sometimes equipped with special guys (Fig. 4, d).

Frames: a - hingeless; b - double-hinged; c - three-hinged; g - double-hinged;

d - hingeless; e - two hinged; g - three-hinged; and - double-hinged with unloading consoles; k - double-hinged with a tightening that absorbs thrust; h - frame height; I - arch lifting boom; l - span; r1 and r2 - radii of curvature of the lower and upper edges of the arch; 0.01 and 02 centers of curvature; - hinges; s - tightening; d - vertical loads on the console.

Metal frames are actively used in construction (Fig. 5, 1, a, b, c, d, e; Fig. 6, a, c).

Steel, reinforced concrete and wooden frames

Reinforced concrete frames can be hingeless, double-hinged, or less often triple-hinged.

For frame spans of up to 30-40 m, they are made of a solid, I-section with stiffeners; for large spans, they are made of lattice. The height of a solid section crossbar is about 1/20-1/25 of the frame span, of a lattice section 1/12-1/15 of the span. Frames can be single-span or multi-span, monolithic or prefabricated. In a prefabricated solution, it is advisable to connect individual frame elements in places with minimal bending moments. In Fig. 5, 2, i, j, and Fig. e 6, c provide examples from the practice of constructing buildings using reinforced concrete frames.

Wooden frames, like wooden beams, are made of nailed or glued elements for spans of up to 24 m. It is advantageous to make them three-hinged to facilitate installation. The height of the crossbar from nail frames is taken to be about 1/12 of the frame span, for glued frames - 1/15 of the span. Examples of the construction of buildings using wooden frames are shown in Fig. 5, l, m, fig. 7.

Rice. 7 Frame of a warehouse building with wooden glued plywood frames

Arches, like frames, are planar spacer structures. They are even more sensitive to uneven precipitation than frames and are made as hingeless, double-hinged or three-hinged (Fig. 4, e, f, g, i, j). The stability of the coating is ensured by the rigid elements of the enclosing part of the coating. For spans of 24-36 m it is possible to use three-hinged arches consisting of two segment trusses(Fig. 8, a). To avoid sagging, hangers are installed.

a - three-hinged wooden arch made of polygonal trusses;

b - lattice wooden arch

Metal arches are made of solid and lattice sections. The height of the crossbar of a solid section of arches is used within 1/50-1/80, of a lattice span 1/30-1/60. The ratio of the lifting boom to the span for all arches is in the range of 1/2-1/4 for a parabolic curve and 1/4-1/8 for a circular curve. In Fig. 8, a, fig. 9, fig. 1, fig. 10, a, b, c, examples from construction practice are presented.

Reinforced concrete arches, like metal arches, can have a solid or lattice cross-section of the crossbar.

The structural height of the cross-section of the crossbar of solid arches is 1/30-1/40 of the span, of lattice arches 1/25-1/30 of the span.

Prefabricated arches of large spans are made in composite form, from two semi-arches, concreted in Fig. e in a horizontal position, and then raised to the design position (example in Fig. 9, 2, a, b, c).

Wooden arches are made from nailed and glued elements. The ratio of the lifting boom to the span for nailed arches is 1/15-1/20, for glued ones - 1/20-1/25 (Fig. 8, a, b, Fig. 10, c, d).

a - arch with tightening on columns; b - supporting the arch on the frames; or buttresses; c - supporting the arch on the foundations

4. Spatial long-span coating structures

Long-span structural systems from different eras share a number of significant features, which makes it possible to consider them as technical progress in construction. The dream of builders and architects is connected with them, to conquer space, to cover the largest possible area. What unites historical and modern curvilinear structures is the search for appropriate shapes, the desire to minimize their weight, the search for optimal load distribution conditions, which leads to the discovery of new materials and potential possibilities.

Spatial long-span covering structures include flat folded coverings, vaults, shells, domes, cross-ribbed coverings, rod structures, pneumatic and awning structures.

Flat folded coverings, shells, cross-ribbed coverings and rod structures are made of rigid materials (reinforced concrete, metal profiles, wood, etc.) Due to the joint work of structures, spatial rigid coverings have a small mass, which reduces the cost of both covering construction and for the installation of supports and foundations.

Hanging (cable-stayed), pneumatic and awning coverings are made of non-rigid materials (metal cables, metal rice membranes, membranes made of synthetic films and fabrics). They, to a much greater extent than spatial rigid structures, ensure a reduction in the volumetric mass of structures and allow for the rapid construction of structures.

Spatial structures make it possible to create a wide variety of forms of buildings and structures. However, the construction of spatial structures requires a more complex organization of construction production and high quality of all construction work.

Of course, it is impossible to give recommendations on the use of certain coating structures for each specific case. The coating as a complex subsystem formation is located in the structure of the structure in close connection with all its other elements, with external and internal environmental influences, with the economic, technical, artistic and aesthetic-style conditions of its formation. But some experience in the use of spatial structures and the results that it gave can help in understanding the place of a particular constructive and technological organization of public buildings. Spatial type structural systems already known in world construction practice make it possible to cover buildings and structures with almost any plan configuration.

1 Folds

A fold is a spatial covering formed by flat mutually intersecting elements. Folds consist of a number of elements repeated in a certain order, supported along the edges and in the span by stiffening diaphragms.

The folds are sawtooth, trapezoidal, made of the same type of triangular planes, tent-shaped (quadrangular and polyhedral) and others (Fig. 11, a, b, c, d).

Folded structures used in cylindrical shells and domes are discussed in the relevant sections.

The folds can be extended beyond the outer supports, forming cantilever overhangs. The thickness of the flat fold element is taken to be about 1/200 of the span, the height of the element is at least 1/10, and the width of the edge is at least 1/5 of the span. Folds usually cover spans up to 50-60 m, and tents up to 24 m.

Folded structures have a number of positive qualities:

simplicity of form and, accordingly, ease of their manufacture;

Great possibilities for factory prefabrication;

saving room height, etc.

An interesting example The application of a flat folded structure of a sawtooth profile is the coating of the laboratory of the Concrete Institute in Detroit (USA) with a size of 29.1 × 11.4 ( Fig. 11, e) project by architects Yamasaki and Leinweber, engineers Amman and Whitney. The covering rests on two longitudinal rows of supports, forming a middle corridor and has cantilever extensions on both sides of the supports, 5.8 m long. The covering is a combination of folds directed in opposite directions. The thickness of the folds is 9.5 cm.

In 1972, during the reconstruction of the Kursky railway station in Moscow, a trapezoidal folded structure was used, which made it possible to cover a waiting room measuring 33 × 200 m (Fig. 11, f).

The most ancient and widespread system of curvilinear covering is the vaulted covering. The vault is a structural system on the basis of which a number of architectural forms of the past (up to the twentieth century) were created, which made it possible to solve the problem of covering a variety of halls with different functional purposes.

Cylindrical and closed vaults are the simplest forms of vault, but the space formed by these coverings is closed, and the form is devoid of plasticity. By introducing formwork into the designs of the trays of these vaults, a visual feeling of lightness is achieved. The inner surface of the vaults, as a rule, was decorated with rich decoration or imitated by a false structure of a wooden suspended ceiling.

A cross vault is formed by cutting from the intersection of two barrel vaults. They were blocked by huge halls of baths and basilicas. The cross vault was widely used in Gothic architecture.

Cross vault is one of the common forms of covering in Russian stone architecture.

Varieties of vaults such as sail vaults, domed vaults, and canopies were widely used.

3 Shells

Thin-walled shells are one of the types of spatial structures and are used in the construction of buildings and structures with large areas (hangars, stadiums, markets, etc.). A thin-walled shell is a curved surface, which, with minimal thickness and, accordingly, minimal mass and material consumption, has a very large bearing capacity, because thanks to its curvilinear shape it acts as a spatial load-bearing structure.

A simple experiment with rice paper shows that a very thin curved plate, due to its curvilinear shape, acquires greater resistance to external forces than the same plate of a flat shape.

Rigid shells can be erected over buildings of any configuration in plan: rectangular, square, round, oval, etc.

Even very complex structures can be divided into a number of similar elements. In factories construction parts Separate technological lines are created for the manufacture of individual structural elements. The developed installation methods make it possible to erect shells and domes using inventory support towers or without auxiliary scaffolding at all, which significantly reduces the construction time of coverings and reduces the cost of installation work.

According to their design schemes, rigid shells are divided into: shells of positive and negative curvature, umbrella shells, vaults and domes.

Shells are made of reinforced concrete, reinforced cement, metal, wood, plastics and other materials that can withstand compressive forces well.

In conventional load-bearing systems, which we discussed earlier, the resistance to emerging forces is concentrated continuously along their entire curved surface, i.e. since this is characteristic of spatial load-bearing systems.

The first reinforced concrete shell dome was built in 1925 in Jena. Its diameter was 40m, this is equal to the diameter of the dome of St. Peter's in Rome. The mass of this shell turned out to be 30 times less than the dome of St. Petra. This is the first example that showed the promising capabilities of the new design principle.

The advent of stress-reinforced concrete, the creation of new calculation methods, the measurement and testing of structures using models, along with the static and economic benefits of their use, all contributed to the rapid spread of shells throughout the world.

Shells have a number of other advantages:

in the coating they simultaneously perform two functions: load-bearing structure and roof;

they are fire-resistant, which in many cases puts them in a more advantageous position even under equal economic conditions;

they have no equal in the variety and originality of forms in the history of architecture;

finally, in comparison with previous vaulted and dome structures, they surpassed them many times in terms of the spans covered.

If the construction of shells in reinforced concrete has become quite widely developed, then in metal and wood these structures still have limited use, since sufficiently simple ones characteristic of metal and wood have not yet been found, structural forms shells.

Shells in metal can be made of all-metal, where the shell simultaneously performs the functions of a load-bearing and enclosing structure in one, two or more layers. With appropriate development, the construction of shells can be reduced to the industrial assembly of large panels.

Single-layer metal shells are made of steel or aluminum rice.a. To increase the rigidity of the shells, transverse ribs are introduced. With a frequent arrangement of transverse ribs connected to each other along the upper and lower belts, a two-layer shell can be obtained.

Shells come in single and double curvature.

To shells single curvature include shells with cylindrical or conical surface(Fig. 12, a, b).

Rice. 12. The most common forms of shells

a - cylinder: 1 - circle, parabola, sinusoid, ellipse (guides); 2 - straight line (generative); b - cone: 1 - any curve; 2 - straight line (generative); d - transfer surface: 1 - parabola (guide); 2 - ellipse, circle (generative); c - surface of rotation (dome): 1-rotation; 2 - circle, ellipse, parabola (generative); Surface of rotation or transfer (spherical shell): 1, 2 - circle, parabola (generators or guides); 3 - circle, parabola (generative); 4 - axis of rotation d - formation of shells of double curvature in one direction: hyperbolic paraboloid: AB-SD, AC-VD - straight lines (guides); 1 - parabola (guide).

Cylindrical shells have a circular, elliptical or parabolic shape and are supported by end stiffening diaphragms, which can be made in the form of walls, trusses, arches or frames. Depending on the length of the shells, they are divided into short ones, in which the span along the longitudinal axis is no more than one and a half wavelengths (span in the transverse direction), and long ones, in which the span along the longitudinal axis is more than one and a half wavelengths (Fig. 13, a , c, d).

Along the longitudinal edges of long cylindrical shells, side elements (stiffening ribs) are provided, in which longitudinal reinforcement is placed, allowing the shell to operate along the longitudinal span like a beam. In addition, the side elements absorb the thrust from the work of the shells in the transverse direction and therefore must have sufficient rigidity in the horizontal direction (Fig. 13, a, e).

The wavelength of a long cylindrical shell usually does not exceed 12 m. The ratio of the lifting boom to the wavelength is taken to be at least 1/7 of the span, and the ratio of the lifting boom to the span length is not less than 1/10.

Prefabricated long cylindrical shells are usually divided into cylindrical sections, side elements and a stiffening diaphragm, the reinforcement of which is welded together and monolied during installation (Fig. 13, e).

It is advisable to use long cylindrical shells for covering large rooms with a rectangular plan. Long shells are usually placed parallel to the short side of the overlapped rectangular space to reduce the span of the shells along the longitudinal axis (Fig. 13, e). The development of long cylindrical shells follows the line of searching for the flattest possible arc with a small lifting boom, which leads to easier conditions for construction work, a reduction in the volume of the building and improved operating conditions.

Particularly advantageous, in terms of structural work, is the arrangement of a sequential row of flat cylindrical shells, since in this case the bending forces acting in the horizontal direction are absorbed by adjacent shells (except for the outer ones).

Let us give examples of the use of long cylindrical shells in construction.

The multi-wavelength long cylindrical shell was made in a garage in Bournemouth (England).

Shell sizes 4 5×90 m, thickness 6.3 cm, the project was carried out by engineer Morgan (Fig. 14, a).

c - hangar of the airfield in Karachi (Pakistan, 1944). The coating is formed by long cylindrical shells 39.6 m long, 10.67 m wide and 62.5 mm thick. The shells rest on a 58 m long purlin, which is a lintel over the hangar gate; g - hangar of the Ministry of Aviation in the Academy of Sciences! lip (1959). To cover the hangar, three cylindrical shells were used, located parallel to the hangar door opening. The length of the shells is 55 m. The depth of the hangar is 32.5 m. The beams that absorb the thrust have a box-shaped section

The covering of the sports hall in Madrid (1935) was designed by the architect Zuazo and the engineer Torroja. The covering is a combination of two long cylindrical shells resting on the end walls and does not require support on the longitudinal walls, which for this reason are made of lightweight materials. Shell length 35 m, span 32.6 m, thickness 8.5 cm (Fig. 14, b).

The airfield hangar in Karachi, built in 1944, is represented by shells whose length is 29.6 m, width 10.67 m and thickness 6.25 cm. The shells rest on a girder with a span of 58 m, which is a lintel over the hangar gate (Fig. 14 , V).

The use of long cylindrical shells is practically limited to spans up to 50 m, since beyond this limit the height of the side elements (rand beams) turns out to be excessively large.

Such shells are often used in industrial construction, but are also used in public buildings. Kaliningradgrazhdanproekt has developed long cylindrical shells with spans of 18 × 24 m, 3 m wide. They are manufactured immediately for the span together with insulation - fibreboard. A layer of waterproofing is applied on top of the finished element at the factory.

Long cylindrical shells are made of reinforced concrete, reinforced cement, steel and aluminum alloys.

Thus, to cover the Moscow railway station in St. Petersburg, a cylindrical shell made of rice aluminum was used. The length of the temperature block is 48 m, width 9 m. The coating is suspended from reinforced concrete supports installed at the inter-track.

Short cylindrical shells, compared to long shells, have a larger wave size and lifting boom. The curvature of short cylindrical shells corresponds to the direction of the largest span of the covered room. These shells act as vaults.

The shape of the curve can be represented by a circular arc or a parabola. Due to the danger of buckling in short shells, transverse stiffeners are introduced in most cases. In addition to the side elements, such shells must have tightening to absorb horizontal transverse forces (Fig. 13, c, e).

Short cylindrical shells for buildings with a grid of columns 24 are widely known × 12 m and 18 × 12 m. They consist of diaphragm trusses, ribbed panels 3 × 12 m and side elements (Fig. 15, a-d).

The structures for the specified spans are recognized as standard.

The use of short cylindrical shells does not require the use of a suspended ceiling.

Conical shells are usually used for roofing trapezoidal buildings or premises. The design features of these shells are the same as long cylindrical shells (Fig. 12, a). An example of an interesting use of this form is the covering of a lakeside restaurant in Georgia (USA), made in the form of a series of reinforced concrete mushroom-shaped cones with a diameter of 9.14 m. The hollow mushroom stems are used to drain rainwater from the surface of the covering. The triangles formed by the edges of three touching mushrooms were covered with reinforced concrete slabs with round holes for skylights in the form of plastic domes.

Rice. 15 Examples of the use of short cylindrical shells made in reinforced concrete

In undulating and folded shells with long spans, significant bending moments occur due to temporary loads from wind, snow, temperature changes, etc.

The necessary reinforcement of such shells was achieved by constructing ribs. A reduction in effort was achieved by switching to wavy and folded profiles of the shell itself. This made it possible to increase the rigidity of the shells and reduce material consumption.

Such designs make it possible to emphasize the contrast between the plane of the enclosing wall, which can be independent of the load-bearing supports, and the covering resting on it. This makes it possible to make large cantilever overhangs in these structures for installing supports, etc. (Kursky railway station in Moscow).

Folds and waves are an interesting plate shape for ceilings and sometimes for walls in interiors.

A wavy shell, when the scale, curvature, and shape are found for it, based on the requirements of architectural aesthetics, can be quite expressive. This type of structure is designed for spans of more than 100 m, which have been applied to cover a wide variety of objects.

Polyhedral folded shell vaults are an example of increasing the rigidity of a cylindrical shell by imparting a polyhedral shape.

The transition from single-curvature shells to double-curvature shells marks a new stage in the development of shells, since the effect of bending forces in them is reduced to a minimum.

Such shells are used in buildings with various plans: square, triangular, rectangular, etc.

A variety of such shells on a round or oval plan is a dome.

Shells of double curvature can be made with both ruffled and flat contours.

Their disadvantages include: an inflated volume of the building being covered, a large roof surface, and not always favorable acoustic characteristics. In the coating it is possible to use light lanterns mainly in the center.

Such shells can be made in monolithic and prefabricated monolithic reinforced concrete.

The spans of these buildings vary between 24-30 m. The stability of the shell is ensured by a system of pre-stressed stiffening beams with a mesh of 12 × 12 m. The shell contour rests on a prestressed belt.

In some cases, it is advisable to cover the halls with tent shells in the shape of a truncated pyramid, made of reinforced concrete. They can rest along the contour, on two sides or corners.

The most common types of double-curvature shells in construction practice are shown in Fig. 12, f, g, h.

The dome is a surface of rotation. The forces in it act in the meridional and latitudinal directions. Compressive stresses arise along the meridian. Along the latitudes, starting from the top, compressive forces also arise, gradually turning into tensile forces, which reach their maximum at the lower edge of the dome. Dome shells can rest on a tensile support ring, on columns - through a system of diaphragms or stiffeners, if the shell has a square or polyhedral shape in plan.

The dome originated in the countries of the East and had, first of all, a utilitarian purpose. In the absence of wood, clay and brick domes served as coverings for dwellings. But gradually, thanks to its exceptional aesthetic and tectonic qualities, the dome acquired independent semantic content as an architectural form. The development of the dome's shape is associated with a constant change in the nature of its geometry. From spherical and spherical shapes, builders move on to pointed ones with complex parabolic shapes.

Domes are spherical and multifaceted, ribbed, smooth, corrugated, wavy (Fig. 16, a). Let's look at the most typical examples of dome shells.

Covering the Sports Palace in Rome (1960), built according to the design of Professor P.L. Nervi for the Olympic Games is a spherical dome made of prefabricated reinforced cement elements with a width of 1.67 to 0.34 m, having a complex spatial shape (Fig. 17, a). The 114 segments of the dome rest on 38 inclined supports (3 segments per 1 support). After completing the monolithic structures and embedding the prefabricated segments, the dome structure began to work as a single whole. The building was built in 2.5 months.

The dome roof of the concert hall in Matsuyama (Japan), designed in 1954 by architect Kenzo Tange and engineer Zibon, is a segment of a ball with a diameter of 50 m, a lifting boom of 6.7 m (Fig. 17, b). There are 123 round holes with a diameter of 60 cm in the covering for overhead lighting of the hall.

The thickness of the shell in the middle is 12 cm, at the supports it is 72 cm. The thickened part of the shell replaces the support ring.

The dome over the auditorium of the theater in Novosibirsk (1932) has a diameter of 55.5 m, a lifting boom of 13.6 m. The thickness of the shell is 8 cm (1/685 of the span). It rests on a ring with a cross-section of 50 × 80 cm (Figure 17, c).

The dome of the exhibition pavilion in Belgrade (Yugoslavia) was built in 1957. The diameter of the dome is 97.5 m with a lifting boom of 12-84 m. The dome is a structure consisting of a monolithic central part with a diameter of 27 m, and an annular, hollow, trapezoidal section of a reinforced concrete beam , on which 80 prefabricated reinforced concrete semi-arches of an I-section rest, supported by three rows of annular shells (Figure 17, d).

The dome of the stadium in Oporto (Portugal), built in 1981, has a diameter of 92 m.

The covering is made of 32 meridianally located ribs resting on triangular frames and 8 reinforced concrete rings. The diameter of the dome in the area of ​​its support on the triangular frames is 72 m, the height of the dome is 15 m. The dome shell is made of concrete with cork filler on a reinforced concrete frame.

At the top of the dome there is a light lantern (Fig. 17, d).

In Fig. 18 shows examples of dome-shells made of metal. The experience of constructing such buildings has shown that they are not without drawbacks. So, the main one is the large construction volume of buildings and the excessively large mass of building structures.

In recent years, the first domed buildings with retractable roofs have appeared.

For example, for the stadium in Pittsburgh (Fig. 18), sector shell elements made of aluminum alloys sliding radially along the surface of the dome were used.

In wooden domes (Fig. 19, a, b, c), the load-bearing structures are sawn or glued wooden elements. In modern flat domes, the main frame elements work in compression, which is why the use of wood is especially advisable.

Since the Middle Ages, wood has been used as a structural material in dome construction. Many wooden domes dating back to the Middle Ages have survived to this day in Western Europe. They often represent an attic covering above the main dome, made of brick. These domes had a powerful system of rigidity connections. Among such domes is, for example, the main dome of the Trinity Church in Leningrad. The dome, with a diameter of 25 m and a lift of 21.31 m, was erected in 1834 and exists to this day. Of the wooden domes of that time, this dome was the largest in the world. It has a typical timber structure consisting of 32 meridional ribs connected by several beams of ring ties.

Rice. 18 Examples of dome-shells made in metal

In 1920-30 In our country, several wooden domes of significant size were erected. Wooden thin-walled domes covered gas tanks with a diameter of 32 m at the Bereznikovsky and Bobrikovsky chemical plants. In Saratov, Ivanovo and Baku, circuses with diameters of 46, 50 and 67 m, respectively, were covered with wooden domes. These domes had a ribbed design, where the ribs were lattice arches (Fig. 19, b).

Modern technology for gluing wood with durable waterproof synthetic adhesives and extensive experience in the production of laminated wood, and its use in construction, have made it possible to introduce wood as a new high-quality material into long-span structures. Wood structures are strong, durable, fire-resistant and economical.

Figure 19. Examples of the use of wooden dome shells

Domes made of laminated wood are used to cover exhibition and concert halls, circuses, stadiums, planetariums and other public buildings. Architectural and structural types of laminated wood domes are very diverse. The most commonly used domes are ribbed domes, domes with a triangular mesh and mesh domes with a crystalline lattice, developed by Professor M.S. Tupolev.

A number of laminated wood domes have been built in the USA and England.

In the state of Montana (USA), a wooden dome with a diameter of 91.5 m with a lifting boom of 15.29 m was erected over the building of a sports center for 15 thousand spectators in 1956 (Fig. 19, c). The supporting frame of the dome consists of 36 meridional ribs with a cross section of 17.5 × 50 cm. The ribs rest on a lower support ring made of rolled profiles and on a compressed upper metal ring. The dome is installed on reinforced concrete columns 12 m high. In each cell, formed by ribs and girders, steel ties are stretched diagonally crosswise. The dome was installed using paired semi-arches along with purlins and ties. Each semi-arch, 45 m long, was assembled on the ground from three parts.

Folded domes are mounted from reinforced cement spatial shells arranged in one or two tiers, or they are made monolithic (Fig. 19, a).

Wave-shaped domes are used for spans of more than 50 m. The surface of the dome is given a wave-like shape to ensure greater rigidity and stability (Fig. 20, a, b).

The covering of the covered market in Royenne (France), built according to the design of architects Simon and Moriseo, engineer Sarget in 1955, is a wavy spherical shell of 13 radially arranged sinus-shaped paraboloids (Fig. 20, a). The diameter of the dome is 50 m, height 10.15 m, wave width 6 m, thickness 10.5 cm. The lower edges of the waves rest directly on the foundation.

The covering of the circus in Bucharest (1960), designed by the Project Bucharest Institute, is a wave-shaped dome with a diameter of 60.6 m, consisting of 16 parabolic wave segments (Fig. 20, b). The thickness of the shell is 7 cm at the top, 12 cm at the supports. The dome rests on 16 pillars connected to each other by a polygonal prestressed reinforced concrete belt that absorbs thrust forces in the dome.

Shells with a transfer surface are used to cover rectangular or polygonal premises. Such shells rest on diaphragms on all sides of the polygon. The surface of the transfer shell is formed by the translational movement of one curve along another, provided that both curves are curved upward and are in two mutually perpendicular planes (Fig. 12, f).

Transfer shells (Fig. 12, d) work in the transverse and longitudinal direction like arches.

Powerful ties suspended under the longitudinal ribs absorb thrust in the direction of the flight. In the transverse direction, the thrust from the shell in the outer spans is absorbed by stiffening diaphragms and side elements, and in the middle spans the thrust is absorbed by neighboring shells. The cross sections of the transfer shells along the entire length of the arch, except for the support zones, are often assumed to be circular (Fig. 16, b).

An example of a shell with a transfer surface is the cover of a rubber factory in Brynmawr (South Wales, England), built in 1947 (Fig. 21, b). The coating consists of 9 rectangular elliptical shells measuring 19 ×26 m. The thickness of the shells is 7.5 cm. The rigidity of the shells is ensured by side diaphragms.

In the support zones, the shell can end with conoidal elements that provide a transition from the circular cross-section of the middle zone to a rectangular one along the line of support.

Using this system, a covering over a car garage with a span of 96 m was built in Leningrad, consisting of 12 vaults, each 12 m wide.

Spherical sail shells are formed when the spherical surface is limited by vertical planes built on the sides of a square. The stiffness diaphragms in this case are the same for all four sides (Fig. 12, c, e, Fig. 16).

Prefabricated ribbed spherical shells size 36 × 36 m are used in the construction of many industrial facilities (Fig. 21, e). This solution uses slabs of four standard sizes: in the middle part, square 3 × 3 m, and to the periphery - rhombic shells, close to the size of a square. These slabs have diagonal working ribs and small thickenings along the contour.

The ends of the reinforcement of the diagonal ribs are exposed. During installation, they are welded using overhead rods. Rods with spiral reinforcement placed on them are placed in the seams between the slabs in the area of ​​corner joints. After this, the seams are sealed.

The spherical covering of the building of the Novosibirsk shopping center has dimensions in plan of 102 × 102 m, the rise of the contour arches is equal to 1/10 of the span. The generatrix curve of the shell has the same rise.

The total rise of the shell is 20.4 m. The surface of the shell is cut taking into account the transfer pattern. In corner areas, the covering slabs are located diagonally in order to place stressed reinforcement in longitudinal (diagonal) joints.

The supporting parts of the corner sections of the coating, which experience the greatest stress, are made of monolithic reinforced concrete.

The coverings of the 1200-seat meeting hall at the Massachusetts Institute of Technology in Boston (USA) were designed by architect Ero Saariner. It is a spherical shell with a diameter of 52 m and has a triangle shape in plan.

The spherical shell of the coating is 1/8 of the spherical surface. Along the contour, the shell rests on three curved load-bearing belts, which transmit forces to supports located at three points (Fig. 21, d). Shell thickness from 9 to 61 cm.

Such a large thickness of the shell at the supports is explained by significant bending moments arising in the shell due to large cutouts, which indicates an unsuccessful design solution.

The covering of the shopping center in Canoe (Hawaii Islands, USA) is made in the form of a spherical shell with a smooth surface measuring 39.01 × 39.01 m. The shell does not have a rigidity diaphragm and is supported by its corners on 4 abutments. Shell thickness 76-254 mm. (Fig. 21, a).

The cover (Spain) of the covered market in Algeciros, built in 1935 according to the design of the engineer Torroja and the architect Arcas, is an octagonal spherical shell with a diameter of 47.6 m.

The eight supports on which the shell rests are connected to each other by a polygonal belt that absorbs thrust from the shell (Fig. 21, c).

5 Shells with opposite direction of curvature

Shells with opposite directions of one and the other curvature are formed by moving a straight line (generator) along two guide curves. These include conoids, unisexual hyperboloids of revolution and hyperbolic paraboloids (Fig. 12, f, g, h).

When a conoid is formed, the generatrix rests on a curve and a straight line (Fig. 12, g). The result is a surface with the opposite direction of one curvature. The conoid is used mainly for shed roofs and makes it possible to obtain many different shapes. The direction of the conoid curve can be a parabola or a circular curve. The conoidal shell in the shade coating allows for natural lighting and ventilation of the premises (Fig. 16, d, e).

The supporting elements of conoid shells can be arches, rand beams and other structures.

The span of such shells ranges from 18 to 60 m. Tensile stresses arising in the conoid shell are transferred to rigid diaphragms. The load of the conoid shell is carried by four supports, usually located at the four corner points of the shell.

An example is the reception and storage building of the covered market in Toulouse (France), built according to the design of engineer Prat. The market is covered with a structure consisting of parabolic reinforced concrete arched trusses with a span of 20 m, with a lifting boom of 10 m and conoid shells 70 mm thick, the distance between the arches is 7 m. Loading platforms located along the longitudinal sides of the building are covered with cylindrical shells in the form of consoles 7 m long, held by cables resting on the arches (Fig. 22, a).

The generatrix of a single-sex hyperboloid of revolution wraps around the axis with which it intersects in an inclined position (Fig. 12, h). When this line moves, two systems of generatrices appear, intersecting on the surface of the shell.

An example of the use of this shell is the stands of the Zarzuela racetrack in Madrid (Fig. 22, b) and the market in Co (France) (Fig. 22, c).

The formation of the surface of a hyperbolic paraboloid (hypara) is determined by systems of non-parallel and non-intersecting straight lines (Fig. 12, h), which are called guide lines. Each point of a hyperbolic paraboloid is the intersection point of two generatrices that make up the surface.

Rice. 22 Examples of the use of conoidal shells and hyperboloids of revolution

With a uniformly distributed load, the stresses at all points on the hypar surface have a constant value. This is explained by the fact that the tensile and compressive forces are the same for each point. This is why hyparas have greater resistance to bulging. When the shell tends to bend under load, the tensile stress in the direction normal to this pressure automatically increases. This makes it possible to produce shells of low thickness, often without edges.

The first static studies of hypars were published in 1935 by the Frenchman Lafaille, but they found practical application only after the Second World War. Boroni in Italy, Ruban in Czechoslovakia, Candela in Mexico, Salvadori in the USA, Sarge in France. The operational and economic advantages of hypars and unlimited aesthetic possibilities create enormous scope for their use.

In Fig. 16, f, g, h, and shows possible combinations of the surfaces of flat hypars.

Rice. 23 Examples of the use of hypars in construction

Covering of the city theater hall in Shizuska (Japan) architect Kenzo Tange, engineer Shoshikatsu Pauobi (Fig. 23, a). The hall has 2,500 seats for spectators. The building is square in plan, with a side equal to 54 m. The shell has the shape of a hyparum, the surface of which is reinforced with stiffening ribs located parallel to the sides of the square every 2.4 m. The entire load from the covering is transferred to two reinforced concrete supports connected to each other under the floor of the hall by reinforced concrete runs. Additional supports for the shell rand beams are thin swinging posts along the building facades. The width of the rand beam is 2.4 m, thickness 60 cm, shell thickness 7.5 cm.

The chapel and park restaurant in Mexico City were designed by engineer Felix Candela. In these structures, combinations of several hyperbolic paraboloids were used (Fig. 23, b, c)

A nightclub in Acapulco (Mexico) was also designed by F. Candela. In this work, 6 hypars were used.

World construction practice is rich in examples of various forms of hypars in construction.

6 Cross-rib and cross-bar coverings

Cross-ribbed roofing is a system of beams or trusses with parallel chords crossing in two and sometimes three directions. These coatings are similar in their performance to the performance of a solid slab. By creating a cross system, it becomes possible to reduce the height of trusses or beams to 1/6-1/24 spans. It should be noted that cross systems are only effective for rectangular rooms with an aspect ratio ranging from 1:1 to 1.25:1. With a further increase in this ratio, the structure loses its advantages, turning into a conventional beam system. In cross systems, it is very advantageous to use consoles with a reach of up to 1/5-1/4 span. Rational support of cross coverings, using the spatial nature of their work, allows you to optimize their use and build coverings of various sizes and supports from the same type of prefabricated elements of factory production.

In cross-ribbed coverings, the distance between the ribs is from 1.5 m to 6 m. Cross-ribbed coverings can be steel, reinforced concrete, or wood.

Cross-ribbed coverings made of reinforced concrete in the form of caissons can be rationally used with spans up to 36 m. For large spans, one should switch to the use of steel or reinforced concrete trusses.

Wooden cross coverings up to 24 sizes × 24 m are made of plywood and bars with glue and nails.

An example of the use of cross trusses can be the project of the Congress Hall in Chicago completed in 1954 by the architect Van Der Rohe (USA). Hall covering dimensions 219.5 × 219.5 m (Fig. 24, a).

Rice. 24 Cross-ribbed coverings made in metal

The height of the hall to the top of the structures is 34 m. The cross structures are made of steel trusses with parallel chords with a diagonal lattice height of 9.1 m. The entire structure rests on 24 supports (6 supports on each side of the square).

In the exhibition pavilion in Sokolniki (Moscow), built in 1960 according to the Mosproekt project, a cross-coating system measuring 46 × 46 m of aluminum trusses supported by 8 columns. The pitch of the trusses is 6 m, height is 2.4 m. The roof is made of aluminum panels 6 m long (Fig. 24, b)

The Institute VNIIZhelezobeton together with TsNIIEPzhilishchi developed an original design of a cross-diagonal covering measuring 64 ×64 m, made of prefabricated reinforced concrete elements. The covering rests on 24 columns located on the sides of a 48 square × 48 m, and consists of a span and a cantilever part with a projection of 8 m. The column spacing is 8 m.

This design found its application in the construction of the House of Furniture on Lomonosovsky Prospekt in Moscow (authors A. Obraztsov, M. Kontridze, V. Antonov, etc.) The entire covering is made of 112 prefabricated solid reinforced concrete elements of an I-section with a length of 11.32 m and 32 similar elements 5.66 m long (Fig. 25). The enclosing element of the coating is a lightweight prefabricated insulated shield, on which a multi-layer waterproofing carpet is laid.

Rod spatial structures made of metal are a further development of planar lattice structures. The principle of a core spatial structure has been known to mankind since ancient times; it was used in Mongolian yurts and in the huts of the inhabitants of tropical Africa, and in frame buildings of the Middle Ages, and in our time - in the structures of a bicycle, an airplane, a crane, etc.

Rod spatial structures have become widespread in many countries around the world. this is explained by the simplicity of their manufacture, ease of installation, and most importantly, the possibility of industrial production. Whatever the shape of the core spatial structure, three types of elements can always be distinguished in it: nodes, connecting rods and zones. connected to each other in a certain order, these elements form flat spatial systems.

Spatial systems of rod structures include:

Core structural slabs (Fig. 26);

Mesh shells (cylindrical and conical shells, transfer shells and domes) (Fig. 27).

Core spatial structures can be single-zone, double-zone or multi-zone. for example, structural slabs are made with two chords, and mesh domes and cylindrical shells for normal spans are made with single chords.

The nodes and connecting rods form the space enclosed between them (zone). zones can be in the form of a tetrahedron, hexahedron (cube), octahedron, dodecahedron, etc. the shape of the zone may or may not provide rigidity to the rod system, for example, the tetrahedron, octahedron and icosahedron are rigid zones. The problem of stability for single-layer mesh shells is associated with the possibility of so-called “snapping” of them like thin-walled shells (Fig. 26).

Rice. 26 Metal rod structures

Corner ? may be significantly less than one hundred degrees. The clicking itself does not lead to the collapse of the entire mesh structure; in this case, the structure acquires a different stable equilibrium structure.

The node connections used in rod structures depend on the design of the rod system. Thus, in single-layer mesh shells, nodal connections with rigid pinching of the rods in the direction normal to the surface should be used to avoid “snapping” of the nodes, and in structural slabs, as in general in multi-belt systems, rigid connection of the rods in the nodes is not required. the design of the nodal connection depends on the spatial arrangement of the rods and the capabilities of the manufacturer.

The most common rod connection systems used in world practice are the following:

The "meko" system (threaded connection using a shaped element - a ball) has become widespread due to its ease of manufacture and installation (Fig. 28, c);

A “space deck” system of pyramidal, prefabricated elements, which in the plane of the upper chord are connected to each other with bolts, and in the plane of the lower chord are connected by braces (Fig. 28, a);

Connecting rods by welding using ring or spherical shaped parts (Fig. 28, b);

Connecting rods using bent gussets on bolts, etc. (Fig. 28, d); core (structural) slabs have the following basic geometric patterns:

Double belt structure with two families of belt rods;

Double belt structure with three families of belt rods;

Double belt structure with four families of belt rods.

The first structure is the simplest and most commonly used structure today. It is characterized by simplicity of nodal connections (no more than nine rods meet in one node) and is convenient for covering rooms with a rectangular plan. The structural height of the structural slab is assumed to be 1/20 ... 1/25 of the span. with normal spans up to 24 m, the height of the slab is 0.96 ... 1.2 m. If the structure is made of rods of the same length, this length is 1.35 ... 1.7 m. The cells of the structural slab with such dimensions can be covered with conventional roofing elements (cold or insulated) without additional purlins or sheathing. with significant spans of the slab, it is necessary to install purlins under the roof, since with a span of 48 m the height of the slab will be about 1.9 m, and the length of the rods will be about 2.7 m. Examples of the use of structural slabs in the construction are shown in Fig. 29. Mesh cylindrical shells are made in the form of rod meshes with identical cells (Fig. 27). The simplest mesh cylindrical shell is formed by bending a flat triangular mesh. but a cylindrical mesh shell can easily be obtained with a rhombic mesh shape. In these shells, the nodes are located on the surface of different radii, which, like double curvature, increases the load-bearing capacity of the shell. This effect can also be achieved in a triangular bar mesh.

Rice. 28 Some types of nodal connections in rod structures

Mesh domes, having a double curvature surface, are usually made of rods of various lengths. their shape is very diverse (Fig. 27, a). Geodesic domes, the creator of which is engineer Futtler (USA), are a structure in which the surface of the dome is divided into equilateral spherical triangles, formed either by rods of various lengths or panels of various sizes. Mesh conical shells are similar in design to mesh domes, however, they are inferior in rigidity. Their advantages are a retractable surface, which makes it easier to cut roofing elements. The geometric structure of mesh conical shells can be built on the shapes of regular polygons, with three, four or five equilateral triangles meeting at the apex of the cone. All rods of the system have the same length, but the angles in adjacent horizontal chords of the shell change. Other forms of mesh shells are shown in Fig. f 27, b, c, e. Roofing coverings in spatial rod structures, such as structural slabs, differ little from those usually used for steel structures. The coatings of mesh shells of single and double curvature are solved differently. When using lightweight thermal insulation materials, these coatings, as a rule, do not meet thermal requirements (cold in winter, hot in summer). As thermal insulation, we can recommend the optimal material - polystyrene foam.

It can be monolithic (pouring roofing method) or prefabricated; it can be placed directly into molds in which reinforced concrete prefabricated roofing elements are made, etc. this material is lightweight (density 200 kg/m 3), fire-resistant and does not require a cement screed. Other semi-rigid and soft synthetic insulation materials are also used.

The most promising at present should be considered the use of mastic colored roofs, since at the same time they solve the problem of waterproofing and the appearance of structures, which is especially important for coatings of double curvature. In our country, mastic “roofing” is used, which makes it possible to obtain different color shades of the roof (developed research project polymer roofing). In structures where the roof surface is not visible, roofing felt carpet or synthetic films and fabrics can be used. good results are obtained by using roofing packages made of corrugated aluminum sheets with rigid synthetic insulation stamped into them.

Covering the roof with metallic rice materials is not economically feasible. Drainage from the roof surface is decided in each case individually.

5. Hanging (cable-stayed) structures

In 1834, the wire rope was invented - a new structural element that has found very wide application in construction due to its remarkable properties - high strength, low weight, flexibility, durability. In construction, wire ropes were first used as load-bearing structures suspension bridges, and then became widespread in long-span suspended coverings.

The development of modern cable-stayed structures began at the end of the 19th century. During the construction of the Nizhny Novgorod exhibition in 1896, Russian engineer V.G. Shukhov was the first to use a spatially working metal structure, where the work of rigid elements in bending was replaced by the work of flexible cables in tension.

1 Hanging covers

Hanging coverings are used on buildings of almost any configuration. The architectural appearance of structures with hanging roofs is varied. For hanging coverings, wires, fibers, rods made of steel, glass, plastics and wood are used. Since the beginning of the century, more than 120 buildings with hanging roofs have been built in our country. Domestic science has created a theory for calculating suspended systems and structures using computers.

Currently, there are coverings with a span of about 500 m. In suspended coverings, approximately 5-6 kg of steel per 1 m is consumed on load-bearing elements (cables). 2covered area. Cable-stayed structures have a high degree of readiness, and their installation is simple.

The stability of suspended coverings is ensured by stabilization (pre-tensioning) of flexible cables (cables). Stabilization of cables can be achieved by loading in single-belt systems, creating double-belt systems (cable trusses) and self-tensioning of cables in cross systems (cable mesh). Depending on the method of stabilization of individual cables, various slabs of suspended structures can be created (Fig. 30, 1).

Suspended coverings of single curvature are systems of single cables and double-belt cable-stayed systems. The system of single cables (Fig. 30, 1, a) is a load-bearing coating structure consisting of parallel elements (cables) forming a concave surface.

To stabilize the cables of this system, prefabricated reinforced concrete slabs. In the case of embedding cables in the coating structure, a hanging shell is obtained. The magnitude of tensile forces in the cables depends on their sag in the middle of the span. the optimal sag value is 1/15-1/20 of the span. Cable-stayed coverings with parallel single cables are used for rectangular buildings. By placing the suspension points of the cables to the support contour at different levels or giving them different sag, it is possible to create a coating with curvature in the longitudinal direction, which will allow external drainage from the coating. A two-belt cable-stayed system, or cable truss, consists of supporting and stabilizing cables with different curvatures. Coatings on them can have a small mass (40-60 kg/m 2). The supporting and stabilizing cables are connected to each other by round rods or cable braces. The advantage of two-belt cable-stayed systems with diagonal ties is that they are very reliable under dynamic influences and have low deformation. The optimal amount of sag (lift) of cable truss chords for the upper chord is 1/17-1/20, for the lower belt 1/20-1/25 span (Fig. 30, Fig. 1, c). In Fig. Figure 31 shows examples of single-curvature cable-stayed roofings. Cable-stayed coverings of double curvature can be represented by a system of single cables and double-belt systems, as well as cross systems (cable mesh). Coverings using systems of single cables are most often performed in rooms with a circular plan and radial placement of cables. The cables are attached at one end to the compressed support ring, and at the other to the stretched central ring (Fig. 30, Fig. 1, b). The option of installation in the center of the support is possible. Double-belt systems are accepted similarly to single-curvature floors.

Rice. 31 Examples of cable-stayed coverings of single curvature

In coverings with a circular plan, the following options for the relative position of the supporting and stabilizing cables are possible: the cables diverge or converge from the central ring to the supporting one, the cables intersect each other, diverging in the center and at the perimeter of the covering (Fig. 30). A cross system (cable meshes) is formed by two intersecting families of parallel cables (bearing and stabilizing). The surface of the coating in this case has a saddle shape (Fig. 30, Fig. 1, d). The prestressing force in the stabilizing cables is transmitted to the supporting cables in the form of concentrated forces applied at the intersection nodes. the use of cross systems makes it possible to obtain various forms of cable-stayed coverings. for cross cable-stayed systems, the optimal value for the lifting boom of the stabilizing cables is 1/12-1/15 of the span, and the sag of the supporting cables is 1/25-1/75 of the span. The construction of such coverings is labor-intensive. It was first used by Matthew Nowitzky in 1950 (North Carolina). The cross system allows the use of lightweight roofing coverings in the form of prefabricated slabs of lightweight concrete or reinforced cement.

In Fig. Figures 31 and 32 show examples of cable-stayed roofings with single and double curvature. The shape of the cable-stayed covering and the outline of the plan of the structure being covered determine the geometry of the supporting contour of the covering and, consequently, the shape of the supporting (supporting) structures. These structures are flat or spatial frames (steel or reinforced concrete) with racks of constant or variable height. elements of the supporting structure are crossbars, racks, struts, cable stays and foundations. support structures must ensure the placement of anchor fastenings of cables (cables), the transfer of reactions from forces in the cables to the base of the structure and the creation of a rigid supporting contour of the coating to limit deformations of the cable system.

In coverings with a rectangular or square plan, the cables (cable trusses) are usually located parallel to each other. Transfer of thrust can be carried out in several ways:

Through rigid beams located in a flat covering on the end diaphragms (solid walls or buttresses); the intermediate posts perceive only part of the vertical components of the forces in the cables (Fig. 33, c);

Transfer of thrust to frames located in the plane of the cables, with transmission of thrust forces directly to rigid frames or buttresses consisting of stretched or compressed rods (racks, struts). Large tensile forces arising in the braces of frame buttresses are perceived using special anchor devices in the ground in the form of massive foundations or conical (hollow or solid) reinforced concrete anchors (Fig. 33, b);

Transmission of thrust through cable stays is most economical way perception of thrust; Guys can be attached to independent posts and anchor foundations or combined with several guys per post or one anchor device (Fig. 33, a).

In circular coverings, cables or cable trusses are arranged radially. When a uniformly distributed load acts on the coating, the forces in all cables are equal, and the outer support ring is evenly compressed. In this case, there is no need to install anchor foundations. When the load is uneven, bending moments may occur in the support ring, which must be taken into account and excessive moments must be avoided.

For circular coverings, three main options for supporting structures are used:

With the transfer of thrust to the horizontal outer support ring (Fig. 33, d);

With the transmission of forces in the cables to the inclined outer ring (Fig. 33, d);

With the transfer of thrust to inclined contour arches resting

onto a number of racks that absorb vertical forces from the coating (Fig. 33, f, g).

To absorb the forces in the arches, their heels rest on massive foundations or are tied with ties. The theory of calculating cable trusses has now been developed quite fully; there are working formulas and computer programs.

2 Suspended cable-stayed structures

Unlike other types of suspended coverings, in suspended coverings the load-bearing cables are located above the roof surface.

The load-bearing system of suspended coverings consists of cables with vertical or inclined suspensions, which carry either light beams or directly the covering slabs.

The cables are fixed to racks braced in the longitudinal and transverse directions.

Suspended ceilings can have any geometric shape and are made of any materials.

In suspended cable-stayed structures, load-bearing posts can be located in one, two or several rows in the longitudinal or transverse directions (Fig. 34).

When installing suspended cable-stayed structures, instead of guys, you can use cantilever extensions of coverings that balance the tension in the cables.

Several examples from practical construction.

A suspended roof with a transparent plastic roof was first built in 1949 over a bus station in Milan (Italy). The inclined covering is suspended by a system of cables from inclined supporting posts. Balance is achieved by special guys attached to the edges of the covering.

Suspended covering over the Olympic stadium in Squawley (USA). The stadium seats 8,000 spectators. Its dimensions in plan 94.82 × 70.80 m. suspended covering consists of eight pairs of inclined box beams of variable cross-section, supported by cables. The cables are supported by 2 rows of racks installed at intervals of 10.11 m. Purlins are laid along the beams, and along them there are box-section slabs 3.8 m long. The supporting cables - cables have a diameter of 57 mm. When designing suspended structures, significant issues are protecting the suspensions from corrosion in the open air and solving the nodes for the passage of the suspensions through the roof. To do this, it is advisable to use galvanized ropes of a closed profile or profile steel, available for periodic inspection and painting to avoid corrosion.

3 Coverings with rigid cables and membranes

A rigid cable is a series of rod elements made of profile metal, hingedly connected to each other and forming a freely sagging thread when the extreme points are secured to the supports. Connecting rigid cables to each other and to supporting structures does not require the use of complex anchor devices and highly qualified labor.

The main advantage of this coating was its high resistance to wind suction and flutter (flexural-torsional vibrations) without installing special wind connections and prestressing. This was achieved through the use of rigid cables and increasing the constant load on the coating.

Hanging shells made of various rice materials (steel, aluminum alloys, synthetic fabrics etc.) are usually called membranes. Membranes can be manufactured at the factory and delivered to the construction site rolled into rolls. One structural element combines load-bearing and enclosing functions.

The effectiveness of membrane coverings increases if pre-tensioning is used to increase their rigidity instead of heavy roofs and special weights. The sag of membrane coverings is assumed to be 1/15-1/25 of the span.

Along the contour, the membrane is suspended from a steel or reinforced concrete support ring.

The membrane is used for any geometric plan shape. For membranes on a rectangular plan, a cylindrical coating surface is used, on a round plan - spherical or conical (the span is limited to 60 m).

4 Combined systems

When designing long-span structures, there are buildings in which it is advisable to use a combination of a simple structural element (for example, beams, arches, slabs) with a tensioned cable. Some slabs of combined designs have been known for a long time. These are truss structures in which the belt-beam works in compression, and the metal rod or cable perceives tensile forces. In more complex structures, it became possible to simplify the structural design and thereby obtain an economic effect compared to traditional long-span structures. An arched cable truss was used in the construction of the Zenit Sports Games Palace in Leningrad. The building is rectangular in plan, dimensions 72 × 126 m. load-bearing frame This hall is designed in the form of ten transverse frames with a pitch of 12 m and two half-timbered end walls. each of the frames was made in the form of a block of two inclined v-shaped columns-struts, four column braces and two arched-cable trusses. The width of each block is 6 m. The reinforced concrete columns-struts are clamped in the base and are hingedly adjacent to the arched-cable truss. The guy columns at the top and bottom are hinged. balancing of thrust forces occurs mainly in the coating itself. This system compares favorably with purely cable-stayed structures, which on a rectangular plan require the installation of guys, buttresses or other special devices. Prestressing the cables will provide a significant reduction in the moments in the arch that arise under certain types of loads.

The cross-section of the steel arch is I-beam, 900 mm high. The shrouds are made of ropes closed type with filler anchors.

A reinforced concrete slab reinforced with trusses was used to cover nine sections with plan dimensions of 12 × 12 m department store in Kyiv. The upper chord of each cell of the system is made up of nine slabs of size 4×4 m. The lower chord is made of crossed reinforcing bars. These rods are hinged to the diagonal ribs of the corner slabs, which allows the forces of the system to be locked inside it, transferring only the vertical load to the column.

5 Structural elements and details of cable-stayed coverings

Wire ropes (ropes). The main structural material of cable-stayed coverings is made of cold-drawn steel wire with a diameter of 0.5-6 mm, with a tensile strength of up to 220 kg/mm 2. There are several types of cables:

Spiral cables (Fig. 35, 1, a), consisting of a central wire on which several rows of round wires are spirally wound sequentially in the left and right directions;

Multi-strand cables (Fig. 35, Fig. 1, b), consisting of a core (hemp rope or wire strand), on which wire strands are wound in a one-way or cross twist (the strands can have a spiral twist) in this case the cable will be called a spiral-stranded one ;

Closed or semi-closed cables (Fig. 35, Fig. 1, c, d), consisting of a core (for example, in the form of a spiral cable), around which rows of shaped wires are wound, ensuring their tight fit (with a semi-closed solution, the cable has one row windings made of round and shaped wires);

Cables (bundles) of parallel wires (Fig. 35, Fig. 1, e), having a rectangular or polygonal cross-section and interconnected through certain distances or enclosed in a common sheath;

Flat ribbon cables (Fig. 35, Fig. 1, e), consisting of a series of twisted cables (usually four-strand) with alternating right or left twist, interconnected by single or double stitching with wire or thin wire strands, require reliable protection against corrosion. The following methods of anti-corrosion protection of cables are possible: galvanizing, paint coatings or lubricants, coating with a plastic sheath, coating with a sheath of rice steel with injection of bitumen or cement mortar into the sheath, concrete coating.

The ends of the cables must be made in such a way as to ensure the strength of the end is not less than the strength of the cable and the transfer of forces from the cable to other structural elements. The traditional type of end fastening of cables is a loop with a braid (Fig. 35, Fig. 2, a), when the end of the cable unravels into strands that are woven into the cable. To ensure uniform transmission of force in the connection, a thimble is inserted into the loop. Along the length, the cables are also spliced ​​with braiding, except for closed joints. Instead of braiding, clamp connections are often used to fasten and splice cables:

Pressing both branches of the cable with loop fastening into an oval coupling made of light metal, the internal dimensions of which correspond to the diameter of the cable (Fig. 35, Fig. 2, b);

Screw connections, when the end of the cable is unraveled into strands, which are laid around a rod with a screw thread, and then pressed into a light metal coupling (Fig. 35, Fig. 2, c);

Fastening by means of clamps (Fig. 35, Fig. 2, e, j), which are not recommended for tensioned cable cables, as they weaken over time;

Fastening of cables with metal filling (Fig. 35, Fig. 2, f, g), when the end of the cable is unraveled, cleaned, degreased and placed in the conical internal cavity of a special coupling-tip, and then the coupling is filled with molten lead or a lead-zinc alloy ( concrete filling is possible);

Wedge fastenings of cables, rarely used in construction;

Turnbuckles (Fig. 35, Fig. 2, d), used to adjust the length of cables during installation and pre-tension them. Anchor units serve to absorb forces in the cables and transfer them to supporting structures. in prestressed cable-stayed coverings they are also used for pre-tensioning of cables. In Fig.e 35, Fig. 2, and shows the anchoring of a radial cable of a circular cable-stayed covering in a compressed support ring. To ensure free movement of the cable when its angle of inclination changes, conical sleeves filled with bitumen are installed in the support ring and the adjacent coating shell. the rigid support ring and the flexible shell are separated by an expansion joint.

Coatings and roofs, depending on the type of cable-stayed system, use a heavy or light coating structure.

Heavy coverings are made of reinforced concrete. their weight reaches 170-200 kg/m 2, for prefabricated coverings, flat or ribbed slabs of rectangular or trapezoidal shape are used. precast slabs are usually suspended between cables, and the seams between the slabs are grouted.

Light coatings weighing 40-60 kg/m 2usually made of large-sized steel or aluminum profiled sheets, which simultaneously serve as load-bearing elements of the fence and roof if thermal insulation is missing or is attached from below. When placing thermal insulation on top of the panels, it is necessary to install an additional roofing covering. It is advisable to make lightweight coatings from light metal panels with insulation placed inside the panels.

6. Transformable and pneumatic coverings

1 Transformable coverings

Transformable coatings are coatings that can be easily assembled, transported to a new location, and even completely replaced with a new design solution.

The reasons for the development of such structures in the architecture of modern public buildings are manifold. These include: the rapid obsolescence of the functions of structures, the emergence of new lightweight and durable building materials, the tendency for people to become closer to the environment, the tactful incorporation of structures into the landscape, and finally, the growing number of buildings for temporary purposes or for the irregular stay of people in them.

In order to create lightweight prefabricated structures, it was necessary, first of all, to abandon enclosing structures made of reinforced concrete, reinforced cement, steel, wood and switch to lightweight fabric and film coverings that protect the premises from weather factors (rain, snow, sun and wind) , but almost do not comfortably solve psychological problems: reliability of protection from bad weather, durability, thermal insulation function, etc. the load-bearing functions of transformable structures are performed using various techniques. Accordingly, they can be divided into three main groups: thermal coverings, pneumatic structures and transformable rigid systems.

2 Tent and pneumatic structures

Tent pneumatic structures are essentially membrane coverings, but the enclosing functions are performed by fabric and film materials, the load-bearing functions are supplemented by systems of cables and masts, or rigid frame structures. In pneumatic structures, the load-bearing function is performed by air or other light gas. pneumatic and awning structures belong to the class of soft shells and can be given any shape. Their peculiarity is the ability to perceive only tensile forces. To strengthen soft shells, steel cables are used, which are made from corrosion-resistant steel or ordinary steel with a polymer coating. Cables made from synthetic and natural fibers are very promising.

Depending on the materials used, soft shells can be divided into two main types:

Isotropic shells (from metal rice and foil, from film and rice plastics or rubber, from non-oriented fibrous materials);

Anisotropic shells (from fabrics and reinforced films, from wire and cable mesh with cells filled with films or fabrics).

According to their design, soft shells have the following varieties:

Pneumatic structures are soft closed shells stabilized by excess air pressure (they, in turn, are divided into pneumatic frame, pneumatic panel and air-supported structures);

Awning coverings in which stability of shape is ensured by an appropriate choice of surface curvature (there are no supporting cables);

Cable-stayed tents are presented in the form of soft shells of single and double curvature, reinforced over the entire surface and along the edges by a system of cables (cable cables) working in conjunction with the tent shell;

Cable-stayed coverings have a main supporting structure in the form of a system of cables (cables) with rice, fabric or film filler for the cable mesh cells, which absorbs only local forces and primarily performs the functions of a fence.

Pneumatic structures appeared in 1946. Pneumatic structures are soft shells, the pre-tension of which is achieved due to air pumped into them. The materials from which they are made are airtight fabrics and reinforced films. They have high tensile strength, but are not able to resist any kind of stress. The fullest use of the structural properties of the material leads to the formation of various forms, but any of the forms must be subject to certain laws. Incorrectly designed pneumatic structures will reveal the architect's mistake by the formation of cracks and folds that distort the shape, or loss of stability.

Therefore, when creating forms of pneumatic structures, it is very important to remain within certain boundaries, beyond which the very nature of soft shells, stressed by internal air pressure, does not allow.

IN different countries, including in our country, dozens of pneumatic structures have been erected for various purposes. In industry, they are used for various types of warehouse structures, in agriculture, livestock farms are built, in civil engineering, they are used for temporary premises: exhibition halls, shopping and entertainment facilities, and sports facilities.

Pneumatic structures are classified into air-supported, air-carrying and combined. Air-supported pneumatic structures are systems in which excess air pressure is created in thousandths of an atmosphere. This pressure is practically not felt by humans and is maintained using low-pressure fans or blowers. An air-supported building consists of the following structural elements: a flexible fabric or plastic shell, anchor devices for supplying air and maintaining a constant pressure difference. The tightness of the structure is ensured by the airtightness of the shell material and tight connection with the base. The entrance airlock has two alternately opening doors, which reduces air consumption during operation of the shell. The base of the air support structure is a contour pipe made of soft material, filled with water or sand, which is located directly on the leveled area. In more capital structures, continuous concrete base, on which the shell is fixed. The options for attaching the shell to the base are varied.

The simplest form of air-supported structures is a spherical dome, the stress in which from the internal air pressure is the same at all points. Cylindrical shells with spherical ends and toroidal shells have become widespread. The shapes of air-supporting shells are determined by their plan. The dimensions of air-supporting structures are limited by the strength of the materials.

To strengthen them, a system of unloading ropes or nets, as well as internal guy wires, is used. Air-carrying structures include those pneumatic structures in which excess air pressure is created in the sealed cavities of the load-bearing elements of pneumatic frames. pneumatic frames can be presented in the form of arches or frames consisting of curved or straight elements.

Structures, the frame of which are arches or frames, are covered with an awning or connected by awning inserts. if necessary, the structure is stabilized using cables or ropes. the low load-bearing capacity of the pneumatic frame sometimes leads to the need to place the pneumatic arches close to each other. at the same time, the structure acquires a new quality, which can be considered as a special type of air-carrying structures - pneumatic panel structures. Their advantage is the combination of load-bearing and enclosing functions, high thermal performance, and increased stability. Another type is a pneumatic lens coating formed by two shells, and air under pressure is supplied into the space between them. It is impossible not to say about reinforced concrete shells erected using pneumatic shells. To do this, fresh concrete mixture is placed on a reinforcement cage located on the ground along the pneumatic shell film. The concrete is covered with a layer of film, and air is supplied to the pneumatic shell laid out on the ground and it, together with the concrete, rises to the design position, where the concrete gains strength. In this way, domed buildings, shallow shells with flat contours and other forms of coverings can be formed.

Transformable rigid systems. When designing public buildings, sometimes it becomes necessary to provide for the extension of the covering and its closure in case of bad weather. The first such structure was the roof dome over the stadium in Pittsburgh (USA). The dome flaps, sliding along the guides, were moved using electric motors by two flaps, rigidly fixed in a reinforced concrete ring and cantilevered over the stadium using a special triangular shape. The Moscow Architectural Institute has developed several options for transformable coverings, in particular a folding cross covering with a plan size of 12 × 12 m and a height of 0.6 m made of rectangular steel pipes. The folding cross structure consists of mutually perpendicular flat lattice trusses. The trusses of one direction are end-to-end rigid type, the trusses of the other direction consist of links located in the space between the rigid trusses.

Sliding lattice spatial covering structures are also being developed at the institute. Cover size 15 × 15 m high 2 m designed in the form of two slabs resting on the corners. The sliding lattice is made in the form of a brace system, consisting of pairs of intersecting corner profile rods, hingedly connected at the intersection points of the node parts, hingedly connecting the ends of the braces. When folded for transportation, the structure measures 1.4 × 1.4 × 2.9 m and a mass of 2.0 tons. Moreover, its volume is 80 times less than the design one.

Elements of pneumatic structures. Air-supported structures include as necessary structural elements: the shell itself, anchor devices for fastening the structure to the ground, fastening the shell itself to the base, entrance exit gateways, systems for maintaining excess air pressure, ventilation systems, lighting, etc.

Shells can have a variety of shapes. The individual shell strips are stitched or glued. if it is necessary to have detachable connections, use zippers, lacing, etc. Anchor devices used to ensure the balance of the system can be in the form of ballast weights (prefabricated and monolithic concrete elements, ballast bags and containers, water hoses, etc.), anchors (screw anchors with a diameter of 100-350 mm, expansion and clamshell anchors , anchor piles and slabs) or permanent structures of the structure. The shell is secured to the base of the structure either using clamping parts or anchor loops, or ballast bags and cables. rigid mount is more reliable, but less economical.

Practice of using air-supported pneumatic structures. The idea of ​​using “air cylinders” to cover rooms was put forward back in 1917 by W. Lanchester. Pneumatic structures were first used in 1945 by the Bearder company (USA) for covering a wide variety of structures (exhibition halls, workshops, granaries, warehouses, swimming pools, greenhouses, etc.). The largest hemispherical shells of this company had a diameter of 50-60 m. The first pneumatic structures were distinguished by shapes dictated not by the requirements of architectural expressiveness, but by considerations of ease of cutting panels. In the time since the installation of the first pneumatic dome, pneumatic structures have quickly and widely spread throughout all countries of the world with a developed polymer chemistry industry.

However, the creative imagination of architects who turned to pneumatic structures sought new forms. in 1960, a traveling exhibition housed under a pneumatic shell toured a number of South American capitals. It was designed by the architect Victor Landi, who should still be considered the pioneer of pneumatic architecture, since he tried to bring the form into line not only with the function of the structure, but also with the general architectural concept. And, indeed, the building had an interesting, spectacular shape and attracted the attention of visitors (Fig. 36). Building length 92 m, maximum width 38 m, height 16.3 m. total covered area 2500 m2 .

This structure is also interesting because the covering is formed by two fabric shells. To keep them at a constant distance from each other, a gradation of internal pressure was used. each of the shells has independent injection sources. The space between the outer and inner shell is divided into eight compartments in order to ensure the load-bearing capacity of the shell in the event of a local rupture of the shell. the air gap between the shells is good insulation from solar overheating, which made it possible to abandon cooling units. Rigid frames are installed at the ends of the shell, into which revolving doors are installed for visitors to enter. Adjacent to the diaphragms are entrance canopies in the form of strong air-carrying vaults. These vaults serve to install two temporary flexible diaphragms that form an airlock when bulky exhibits and equipment are brought into the pavilion.

The shape of the structure and the use of fabric shells provide good acoustic conditions. The total weight of the structure, including all metal parts (doors, blowers, fastenings, etc.) is 28 tons. during transportation the building occupies a volume of 875 m 3and fits in one railway carriage. The construction of the structure requires 3-4 working days with 12 workers. All installation is carried out on the ground without the use of crane equipment. The shell fills with air in 30 minutes and is designed to withstand wind loads of up to 113 km/h. The author of the pavilion project is architect V. Landi.

The space radio communication station in Raisting (Germany), built according to the design of engineer W. Baird (USA) in 1964, has a soft shell with a diameter of 48 m, made of two-layer Dacron fabric coated with Hypalon. The panels of fabric in the layers are located at an angle of 45 degrees to each other,

This gives the shell some shear rigidity. The internal pressure in the shell can be in the range of 37-150 mm water column (Fig. 36). The Fuji exhibition pavilion at the Osaka World Exhibition (1970) was designed by the architect Murata and is an example of a building solution using progressive technical solutions. The pavilion's covering consists of 16 air hoses-arches with a diameter of 4 m and a length of 72 m each, connected to each other through 5.0 m. Their outer surface is covered with neoprene rubber. Excessive pressure in arched sleeves is 0.08-0.25 atm. Between every two arches two tensioned steel cables are laid to stabilize the entire structure (Fig. 37).

Architect V. Lundy and engineer Baird designed several pneumatic domes for the 1964 New York World's Fair to house restaurants. the domes were arranged in the form of a pyramid or spheres. shells made of bright colored films had a fantastically elegant appearance.

The covering of the summer theater in Boston (USA), made by engineer W. Brand in 1959, is a circular disk-shaped shell with a diameter of 43.5 m and a height in the center of 6 m. A cable is embedded in the edge of the shell, which is attached at certain points to the supporting ring made of steel profiles. the excess internal air pressure in the shell is maintained by two continuously operating blowers and is 25 mm of water column. shell structure weight 1.22 kg/m 2. The covering is removed for the winter.

Pavilion at the agricultural exhibition in Lausanne (Switzerland). The author of the project is F. Otto (Stuttgart), the company "Stromeyer" (Germany). The covering in the form of “sails” of a hyperbolic parabolic shape is a shell made of reinforced polyvinyl chloride film, reinforced by a system of intersecting prestressed cables, which are attached to anchors and steel masts 16.5 m high. The span is 25 m (Fig. 38, a). Open audience at the agricultural exhibition in Markkleeberg (GDR). Authors: association "Devag", Bauer (Leipzig), Rühle (Dresden). Folded covering in the form of a system of prestressed wire ropes with a diameter of 8, 10 and 15 mm with a sheath stretched between them. The covering is suspended from 16 flexible steel posts and secured with guy wires to 16 anchor bolts. The covering is designed as a cable-stayed structure for wind pressure and slope equal to 60 kg/m 2(Fig. 38) The history of the centuries-old development of world construction art testifies to the great role played by spatial structures in public buildings. In many outstanding works of architecture, spatial structures are an integral part, organically fitting into a single whole. The efforts of scientists, designers and builders should be aimed at creating structures that would open up wide opportunities for various functional organization buildings, to improve design solutions not only from the engineering side, but also from the point of view of improving their architectural and artistic qualities. The whole problem must be solved comprehensively, starting with the study of the physical and mechanical properties of new materials and ending with issues of interior composition. This will allow architects and engineers to approach the solution of the main task - the mass construction of functionally and structurally justified, economical and architecturally expressive public buildings and structures for various purposes, worthy of the modern era.

Used Books

1.Buildings with long-span structures - A.V. Demina

.Long-span roofing structures for public and industrial buildings - Zverev A.N.

Internet resources:

.#"justify">. #"justify">. #"justify">. http://www.bibliotekar.ru/spravochnik-129-tehnologia/96.htm - electronic library.

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Question 59. Design solutions for long-span systems. Loads acting on long-span structures. Layout of frames for long-span coverings

The frames of long-span roofs with beam and frame load-bearing systems have a layout scheme close to the frames of industrial buildings. For large spans and the absence of crane beams, it is advisable to increase the distances between the main load-bearing structures to 12-18 m. The systems of vertical and horizontal connections have the same purposes as in industrial buildings and are arranged in a similar way.

The layout of frame coverings can be transverse when load-bearing frames are placed across the building, and longitudinal, typical for hangars. With a longitudinal layout, the main supporting frame is placed in the direction of the larger dimension of the building plan and the transverse trusses rest on it.

The upper and lower chords of the supporting frames and transverse trusses are untied with cross braces, ensuring their stability.

In arched systems, the pitch of the arches is 12 m or more; The main purlins are laid along the arches, on which the transverse ribs supporting the roof deck rest.

For large spans and heights of the main load-bearing systems (frames, arches), spatially stable block structures are used by pairing adjacent flat frames or arches (Fig. 8), as well as by using triangular sections of arches. The arches are connected in the key by longitudinal connections, the importance of which for the rigidity of the structure is especially great when the lifting boom of the arches is large, when their overall deformability increases.

The transverse braces located between the outer pair of arches are calculated on the wind pressure transmitted from the end wall of the arched covering.

QUESTION 60. Long-span beam structures. Their advantages and disadvantages. Constructive decisions. Loads acting on beam structures. Fundamentals of calculation and design of beam structures.

Beam structures

Long-span beam structures are used in cases where supports cannot withstand thrust forces.

Beam systems for large spans are heavier than frame or arch systems, but are easier to manufacture and install.

Beam systems are used mainly in public buildings - theaters, concert halls, sports facilities.

The main load-bearing elements of beam systems used for spans of 50-70 m or more are trusses; Solid beams with large spans are unprofitable in terms of metal consumption.

Main advantages beam structures are characterized by precise operation, absence of thrust forces and insensitivity to support settlements. Main disadvantage– relatively high consumption of steel and high height, caused by large flying moments and rigidity requirements.

Rice. 1, 2, 3

The cross-sections of the rods of long-span trusses with forces in the rods exceeding 4000-5000 kN are usually taken to be composite of welded I-beams or rolled sections.

The high height of the trusses does not allow them to be transported by rail in the form of assembled shipping elements, so they are supplied for installation in bulk and consolidated on site.

The elements are connected by welding or high-strength bolts. High-precision bolts and rivets should not be used because they are labor intensive.

Long-span trusses are calculated and their sections are selected in the same way as light trusses of industrial buildings.

Due to large support reactions, it becomes necessary to transmit them strictly along the axis of the truss unit, otherwise significant additional stresses may arise.

For spans of 60-90m, the mutual displacement of the supports becomes significant due to the deflection of the truss and its temperature deformations. In this case, one of the supports can be a roller (Fig. 6), allowing free horizontal movements.

If the trusses are installed on high flexible columns, then even with spans of up to 90 m, both supports can be stationary due to compliance upper parts columns

Long-span beam systems can consist of triangular trusses with prestressing, which are convenient to manufacture, transport and install (Fig. 7).

The inclusion of a reinforced concrete slab laid along the upper chords of the truss in joint compression work, the use of tubular rods and prestressing make such trusses economical in terms of metal consumption.

Steel sheets are included in the design sections of the upper and lower chords of the trusses.

In order for a thin sheet to work under compression, a preliminary tensile stress is created in it that is greater than the compressive stress from the load.

QUESTION 61. Frame long-span structures. Their advantages and disadvantages. Constructive decisions. Loads acting on frame structures. Fundamentals of calculation and design of frame structures.

Frame structures

Frames spanning large spans can be double-hinged or hingeless.

Hingeless frames are more rigid, more economical in metal consumption and more convenient to install; however, they require more massive foundations with dense bases for them and are more sensitive to temperature influences and uneven settlements of the supports.

Frame structures, compared to beam structures, are more economical in terms of metal consumption and are more rigid, due to which the height of the frame crossbar is lower than the height of beam trusses.

In long-span coverings, both continuous and through frames are used.

Solid frames are rarely used for small spans (50-60 m), their advantages: less labor intensity, transportability and the ability to reduce the height of the room.

The most commonly used frames are hinged frames. It is recommended to take the height of the frame crossbar equal to: with through trusses 1/12-1/18 of the span, with solid crossbars 1/20 - 1/30 of the span.

Frames are calculated using structural mechanics methods. To simplify the calculations, lightweight through frames can be reduced to their equivalent solid frames.

Heavy through frames (such as heavy trusses) must be designed as lattice systems, taking into account the deformation of all lattice rods.

For large spans (more than 50 m) and low rigid posts, it is necessary to calculate the frames for temperature effects.

Crossbars and racks of solid frames have solid I-sections; their load-bearing capacity is checked using formulas for eccentrically compressed rods.

In order to simplify the calculation of lattice frames, their expansion can be determined as for a solid frame.

Using an approximate calculation, preliminary sections of the frame chords are established;

determine the moments of inertia of cross-sections of crossbars and racks using approximate formulas;

calculate the frame using methods structural mechanics; the design diagram of the frame should be taken along the geometric axes;

Having determined the support reactions, the calculated forces in all the rods are found, according to which their sections are finally selected.

The types of sections, design of nodes and connections of frame trusses are the same as for heavy trusses of beam structures.

Another artificial method of unloading the crossbar is the displacement of the supporting hinges in the double-hinged frame from the axis of the rack inward. In this case, vertical support reactions create additional moments that unload the crossbar.

Federal Agency for Education

Ufa State Petroleum Technical University

Faculty of Architecture and Civil Engineering

I.V. Fedortsev, E.A. Sultanova

Construction technology

coating structures

long-span buildings

(tutorial)

Approved by the decision of the Academic Council of USPTU as

training manual (protocol dated _________No. _______)

Reviewers:

____________________________________________________________________________________________________________________

Fedortsev I.V., Sultanova E.A.

Technology of erection of roof structures for long-span buildings: Textbook / I.V. Fedortsev, E.A. Sultanova. – Ufa: Publishing House of USNTU, 2008. – p. ______

ISBN – 5 – 9492 – 055 – 1.

The textbook “Technology for the construction of covering structures for long-span buildings” was developed as the main educational and methodological guide for students of the specialty “Industrial and Civil Engineering” when studying the special discipline “Technology for the construction of buildings and structures” (TVZS).

Contains systematized material of existing experience in the construction of such long-span structures as: beams, frames, arches, cable-stayed, membrane, structural slabs, domes, awnings, etc. The organization and technology of installation processes during the construction of these buildings and structures is set out in the form of clear technological regulations for the work performed in a certain technological sequence with sufficient “detail” of installation processes in the form of “technological maps” and work mechanization schemes. The latter can be used as fundamental recommendations for the development of organizational and technological documentation when designing a work project for specific objects.

Of particular interest is the experience presented in the “Manual” in the installation of the arched covering of the ice palace in the city of Ufa, the construction method of which was for the first time in the practice of constructing such large-span buildings implemented by the construction and installation divisions of Bashkortostan according to the project and by the forces of Vostokneftezavodmontazh OJSC. The manual contains conclusions and control questions for each type of construction, allowing the user to independently assess the assimilation of the material presented in it.

Intended for students of construction specialties of USPTU when studying courses TVZS, TVBzd and TSMR, students of IPK USPTU and construction organizations and departments, one way or another, related to the construction of long-span buildings and structures.

I.V. Fedortsev, E.A. Sultanova

ISBN – 5 – 9492 – 055 – 1 UDC 697.3

INTRODUCTION

Long-span buildings are those in which the distance between the supports of the load-bearing structures of the roof is more than 40 m.

Systems spanning large spans are most often designed as single-span ones, which follows from the main fundamental requirement - the absence of intermediate supports.

In industrial construction, these are, as a rule, assembly shops of shipbuilding, aircraft, and machine-building plants. In civil - exhibition halls, pavilions, concert halls and sports facilities. Experience in the design and construction of long-span pavements shows that the most difficult task in their construction is the installation of the pavement structures.

Load-bearing structures for covering large spans are statically divided into beam, frame, arch, structural, dome, folded, hanging, combined and mesh. All of them are made mainly of steel and aluminum, reinforced concrete, wood, plastics and airtight fabrics. The capabilities and scope of application of spatial structures are determined by their structural design and span size.

When choosing the type of building and structure, an important, often decisive factor is the method of their construction. This is due to the fact that existing mechanization means and traditional installation methods are not always suitable for long-span structures. Therefore, the costs of constructing such buildings significantly exceed the costs of constructing standard traditional structures. The theory and practice of constructing long-span structures in our country and abroad have shown that the greatest reserve for increasing the efficiency of such construction in modern conditions lies in improving the organizational and technological aspects of construction, installation manufacturability and architectural and structural solutions. Installation manufacturability is understood as a property of a design that determines its compliance with the requirements of installation technology and makes it possible to most simply, with the least amount of labor, time and production means, carry out their manufacture, transportation and installation while complying with safety and product quality requirements. An example of such a comprehensive engineering-based organizational and technological solution for the installation of a long-span building in the “Manual” is the experience presented in the construction of an anniversary facility in Bashkortostan - the Ufa Arena ice palace. The uniqueness of the installation of the arched roof of the structure lies in the original organization of assembly and installation processes proposed by Vostokneftezavodmontazh OJSC, which are carried out not on the ground, as usual, but at design marks (20 m) with the subsequent “pushing” of a fully enlarged block weighing more than 500 tons using a system of hydraulic jacks. This installation method, first developed by OJSC VNZM, ensured the “optimal” time frame for the construction of the anniversary facility and, most importantly, allowed the contractor’s heavy equipment to construction equipment carry out the assembly and installation of massive structures directly in the design position. The use of an alternative, in this case, as an option, the traditional method of “pushing” would require the use of more powerful installation cranes (SKG-160), which was practically impossible in the conditions of the existing infrastructure of the city microdistrict where the ice palace was being built.

The characteristics of long-span structures as a set of their design parameters, material of manufacture and overall dimensions are considered below according to the following types of these structures, namely:

Beam;

Arched;

Structural boards;

Cable-stayed systems;

Membrane coatings;

Tent structures;

Tent coverings.

1 Classification of long-span structures

The classification of long-span structures by types of structural schemes for covering buildings and structures is given in Table. 1, containing basic information characterizing the scope of their application and the range of spans covered by these systems. A brief summary of each type of long-span structures, differentiated by span size, allows us to systematize their inherent advantages and disadvantages and, ultimately, determine the possible “rating” of a particular roofing solution for the building being designed.

Beam coverings- consist of main transverse spatial and flat intermediate beams of structures - purlins. They are characterized by the absence of thrust from the coating structure, which significantly “simplify” the nature of the work of the load-bearing elements of the frame and foundations. The main disadvantage is the high consumption of steel and the significant construction height of the span structures themselves. Therefore, they can be used in spans up to 100 m and, mainly, in industries characterized by the need to use heavy overhead cranes.

Frame coverings Compared to beams, they are characterized by lower mass, greater rigidity and lower construction height. Can be used in buildings with a span of up to 120 m.

Arched coverings According to the static scheme, they are divided into 2 x, 3 x and hingeless. They have less weight than beam and frame ones, but more

Possibility of using spatial structures

Table 1

difficult to manufacture and install. The qualitative characteristics of arches mainly depend on their height and outline. The optimal height of the arch is 1/4 ... 1/6 span. The best outline is if the geometric axis coincides with the pressure curve.

The sections of the arches are made lattice or solid with a height of 1/30 ... 1/60 and 1/50 ... 1/80 of the span, respectively. Arched coverings are used for spans up to 200 m.

Spatial coverage characterized by the fact that the axes of all load-bearing elements do not lie in the same plane. They are divided into: domes and shells, characterized as three-dimensional load-bearing structures, distinguished by spatial operation and consisting of surfaces of single or double curvature. The shell is understood as a structure, the shape of which represents a curved surface with a fairly small thickness compared to the surface itself. The main difference between shells and vaults is that both tensile and compressive forces arise in them.

Ribbed domes consist of a system of flat trusses connected at the bottom and top by support rings. The upper chords of the trusses form a surface of rotation (spherical, parabolic). Such a dome is a spacer system in which the lower ring is subjected to tension, and the upper ring is subjected to compression.

Ribbed-ring domes are formed by ribbed semi-arches resting on the lower ring. The height ribs are connected by horizontal ring beams. Curvilinear slabs of lightweight concrete or steel decking can be laid along the load-bearing ribs. The support ring is usually reinforced concrete and prestressed.

Ribbed-ring domes with lattice connections are designed mainly from metal structures. The introduction of diagonal connections into the system of ribbed-ring elements allows for a more rational distribution of compressive-tensile and bending forces, which ensures low metal consumption and the cost of the dome covering itself.

Structural coatings used to cover large spans for industrial and civil purposes. These are spatially core systems, characterized by the fact that during their formation it becomes possible to use repeatedly repeating elements. The most widespread structures are the following types: TsNIISK, “Kislovodsk”, “Berlin”, “MARCHI”, etc.

Hanging covers(guys And membranes) – the main load-bearing elements are flexible steel ropes or thin-walled sheet metal structures stretched orthogonally onto the supporting contours.

Cables and membranes differ significantly from traditional structures. Their advantages include: stretched elements are effectively used over the entire cross-sectional area; the supporting structure is light in weight; the construction of these structures does not require the installation of scaffolding and hanging scaffolding. The larger the span of the building, the more economical the coating design. However, they also have their own disadvantages:

Increased deformability of the coating. To ensure the rigidity of the coating, it is necessary to take additional design solutions by introducing stabilizing elements;

The need to arrange a special support structure in the form of a support contour to absorb the “thrust” from the cables or membrane, which increases the cost of the coating.

The atrium of one of the American hotels owned by Gaylord Hotels

the future comes from the present
and is determined by the path we choose today

Long-span translucent structures are becoming an integral part of urban architecture of the 21st century. The best architects today are increasingly creating amazing complexes of buildings, the center of attraction in which, a certain spatial core, is large atrium spaces - voluminous, filled with light and comfort, well protected from negative external influences and covered with reliable translucent coatings.
Further active development of such structures will probably be able in the near future not only to maximally expand the comfortable and safe space of the human environment, but will also make it possible in the future to change the appearance of our cities and improve their current condition.

Architecture of the era of globalization

At all times in their history, people have sought to protect and protect themselves from numerous unfavorable and dangerous influences from their environment. Heat and cold, rain and wind, predatory animals and wild people have always been a known problem for a quiet human life. Therefore, from ancient times, our ancestors began to build shelters for themselves, which, by creating an artificial environment protected from external influences, brought more of the desired comfort and safety into their lives. And the emerging architecture, as an amazing and excellent instrument of these creative human actions, from its very inception and at all stages of development, tried to make maximum use of the available technical capabilities and existing aesthetic views in society to better satisfy these important human needs: both in comfort and in security.

Today, an era of unprecedented technological development has arrived, and in the construction industry this has made it possible to implement almost any, the most daring architectural ideas. In this regard, the main factors limiting the implementation of all significant projects of modern architects today are often no longer the lack of technical capabilities for the construction of a large and complex object, but only some of our subjective ideas about it, such as: the insufficient usefulness of the future structure, its low demand and low profitability, or the future construction time is too long and the selling price is high. At the same time, with the beginning of a boom in the implementation of the principles of “sustainable development” and “green building” throughout the world, the presence of the factor of environmental sustainability of buildings is also gaining more and more weight for their construction.

With wide technical opportunities opening up for the development of architecture of the 21st century, modern architects in their work, it seems, should begin to take more into account the significant impact that their projects have on the development of the urban environment. It is obvious that modern megacities, having become hostages of the past path of their development and the ongoing approach to their development, are gradually becoming more and more a multifactorial problem for the peace and safety of their residents.

Having entered the era of globalization, our world has changed greatly in recent years, and today it is hardly possible to find reasonable justifications for the continuing formation of crowded living of people in separate points of space. Our society is beginning to understand the destructiveness of this process, but urban architecture, unfortunately, still continues to follow the path of creating high-rise projects and densifying urban development, thereby provoking an even greater concentration of the population in certain points of an already excessively overpopulated space.

At the same time, having modern technologies and using its colossal impact on the life of society, the architecture of the 21st century can not only maximize the comfortable and safe space of the human environment, but also can and should try, step by step, to radically change the appearance of our cities and improve their current state. In addition, Architecture, as the unsurpassed master of space, time and the imagination of many people, will certainly increasingly contribute to the emergence of fundamentally new eco-cities and eco-villages.

City under the dome

The dream of translucent coatings that protect streets and city blocks from rain and snow originated with people a long time ago. But only with the advent of the industrial revolution, which brought broad technical and financial opportunities, the implementation of such projects becomes feasible. It was only during the second half of the 19th century that large glass-covered arcades with rows of expensive shops and cozy cafes appeared in most of the main cities of Europe and America. And one of the very first notable pearls of that period of development of large glazed atrium spaces is the famous Galleria Vittorio Emmanuel II in Milan, open to visitors back in 1877.

Fig.2. Gallery of Victor Emmanuel II in Milan.

Since progress cannot be stopped, actively participating in it, and not remaining on the margins of history, is the task of all great countries. That is why, since the second half of the twentieth century, construction science in the USSR, the USA and some other countries has already been seriously working on the possibility of protecting their cities with large translucent domes from: undesirable weather phenomena, negative features of the local climate, excessive levels of solar radiation and others unfavorable for human influences from the external environment. In recent years, we can add to the list of factors stimulating further research in this direction: rapid and unpredictable climate changes on the planet, an alarming increase in environmental pollution, growing threats of extremism, as well as the desire of people to reduce the extremely high energy costs of their cities.

Today, the creation of long-span translucent protective structures (hereinafter referred to as LSPS), in which there are many natural light and comfort, intensified like never before. New ideas are emerging and a variety of unique projects are being created - such as the Dome over Houston - and some of these amazing projects are already being implemented. Thus, in Astana, with the help of English engineers and Turkish builders, a 100-meter (excluding the height of the spire) translucent tent was built, which housed the largest and most presentable shopping and entertainment center in Kazakhstan.

An even more amazing and grandiose structure was created in Germany - this is the Tropical Islands water entertainment center, which has an internal volume of about 5.5 million cubic meters. m and is rightfully the largest translucent building in the world by this indicator today.

Fig.3-5. Water entertainment center "Tropical Islands" in Germany

An important stage in the development of volumetric translucent structures was the scientific substantiation of the possibility of their tangible efficiency - both in energy efficiency and in a significant reduction in heat loss, while simultaneously significantly expanding the newly created comfortable and in-demand public space.

The credit for this justification belongs to English and American architects and scientists, but, first of all, we can highlight the work of Terry Farrell and Rolf Lebens, who at the border of the 70-80s of the twentieth century created the concept of “buffer thinking”. The result of this concept was the active introduction of the “buffer effect” or the “double enclosure principle” into world architectural practice.

When researching the issue of the possibility of creating efficient large atrium spaces, warming, cooling and transformable types of atriums were identified. Only a little more than 30 years have passed since then, but even during this short period of time, modern atrium spaces have conquered the entire civilized architectural world (photos of American atriums given in this article are a small fraction of the existing multitude and variety of atrium spaces built over the years). Unfortunately, modern Russia, in this sense, does not yet have great achievements.

Agreeing with the existing arguments of experts on the advisability of using large atrium spaces in modern architecture, and without trying to dispute their conclusions, the author of the article further proposes to consider the possibility of how, with the help of multi-belt cable structures, to create (cover) such spaces cheaper and more reliably, and Also, we are not particularly limited by the size of atriums, introducing new technology for covering large spans. It seems that in Russian conditions, even just the creation of the simplest second fence (buffer space) around city blocks will make it possible to wisely use those numerous heat losses of covered buildings, which will not be irretrievably dissolved in the surrounding space, but will provide heating for the resulting atrium spaces. Only due to a high-quality translucent protective coating, the temperature in such atrium spaces in winter can be 10-15 degrees higher than outside.

In the summer, in addition to reasonable, adjustable partial shading of the internal space, from excessive solar radiation and overheating, it is possible to provide for the opening of ventilation openings in the translucent covering, as well as to implement other well-known and effective methods of creating a comfortable microclimate inside the entire translucent complex. Obviously, creating a comfortable and stable microclimate in one large enclosed space will be much easier and cheaper than providing the same comfortable conditions simultaneously in thousands of small rooms.
The very nature of volumetric translucent structures encourages us to discard some of the stereotypes of our thinking when solving such problems, and take a fresh look at the possibility of creating a comfortable environment in the new conditions of large volumetric spaces. At the same time, there are already new effective technical solutions, using the important advantages of large spaces and making it possible to provide stable comfortable conditions for the entire internal space of the BSZS at significantly lower energy costs.

Meanwhile, the possibilities for using multi-belt cable coverings seem to be wider. Thus, the process of building eco-cities, which is still in its infancy and timidly announces itself, also cannot be imagined without large-span translucent structures. I would like to think that the 21st century, having appreciated the new large-span translucent architecture, will actively develop and improve it, and will also try to use it to quickly make a breakthrough in urban planning, replacing the dull, energy-inefficient and unsafe concrete jungle of modern megacities with convenient, comfortable and environmentally friendly cities.

Rice. 6-11 Masdar City (illustrations by Foster + Partners).

The most ambitious and pompous eco-city project today can be called Masdar City. This is probably the first truly serious attempt at an integrated approach to organizing the city of the future - powered by energy from renewable sources (sun, wind, etc.) and having a sustainable ecological environment with minimal carbon dioxide emissions into the atmosphere, as well as a system for the complete recycling of waste from urban activities.
Unfortunately, the location chosen for the construction of Masdar City was not the most successful, and future residents and operating organizations will still have to experience some of the inconveniences of the location of this corner of the desert. It is so obvious that the technical solutions included in the city project will not be able to fully cope with the 50-degree summer heat (the exception will be closed spaces, including all atriums). The rainy periods in December-January, and later the season of heavy fog, will also not be comfortable for the residents of the new city. And if we remember the fairly frequent winter-spring sandstorms in that part of the desert, we will understand that without large-span translucent coatings covering and protecting city blocks from these local natural phenomena, city residents will periodically have to experience certain inconveniences.
The concept proposed below for the construction of large-span translucent structures fits well into projects like Masdar City and, it seems, is quite capable of helping such projects save money on both the construction and operation of modern cities. And also to make these cities safer and more comfortable.

Figure 6-11. This is how the future Masdar City can be seen in colorful advertising brochures and magazine illustrations (illustrations by Foster + Partners).

In 2012, Russian engineers developed a concept for covering large spans that is technically accessible today and effective in implementation, allowing for the construction of a variety of large-span buildings and structures. The idea is to create a multi-belt cable covering over a complex of buildings, which, covering large spans between supporting buildings, will be able to carry any design load and create a single durable and reliable translucent covering for the entire complex. The coating will provide the ability to maintain constant and comfortable parameters for humans in the enclosed internal space of such an object: temperature, humidity, air mobility and cleanliness, illumination, safety, etc.
The idea of ​​multi-belt cable systems is based on the well-known principles of suspended structures, which have been widely used in the world for the construction of long-span buildings and structures for more than half a century. But hanging structures have not become more widespread in long-span construction due to some of their shortcomings. Thus, large-span buildings with suspended roof structures, as a rule, cannot provide a slope of the roof to the outside of the building, which creates additional difficulties with the removal of precipitation from the roof. In addition, by creating very significant horizontal loads in high supports, cable-stayed structures force builders to solve this problem with additional financial investments into powerful buttresses for these loads. But the main disadvantage of hanging structures is their high deformability under the influence of local loads.

Multi-belt cable systems managed to overcome the listed disadvantages of long-span cable-stayed coverings and even created the opportunity to successfully cover much larger spans, which today can give a new impetus to the development of long-span construction.

It is known that the covering of large spans at all times in the development of our civilization interested and attracted the attention of not only architects and builders, but also ordinary people. The creation of majestic structures with large spans has always been an indicator of the advanced development of engineering, as well as the technical and financial power of countries capable of building such structures.

What is multi-belt rope covering and how does it work?

To understand how a multi-belt cable covering works, one must imagine the design of any known long-span covering that was used to block the span between two supporting buildings. (for example, spatial cross-bar slab). If the span is large enough, then this coating will inevitably bend under its own weight, and when exposed to additional external loads (from snow, wind, etc.) it may collapse. But to prevent this from happening and the long-span covering from collapsing, we stretch high-strength steel cables underneath it in several rows (belts), from one supporting building to another, tension them and install them (at certain distances along the length of the cables) between the belts of the resulting cable systems, spacer posts, and between adjacent cables in all belts of the cable system - spacers and/or guy wires. Multi-banding helps ensure that at any span length the cable system is biconvex and supports the sagging covering in question from below.

At the same time, in the coating, due to the tension of the cables and the work of the spacer posts, not only will the resulting deflection disappear, but also a deflection will appear with the opposite sign - upward. This allows the coating not only not to collapse under the influence of extreme loads on it, but, on the contrary, will contribute to the possibility of it accepting significant additional loads, in accordance with the design characteristics of the cable system that will be assigned to it by the project.
Experts understand that a system of prestressed cable structures supporting a rigid, durable and stable coating is impossible without powerful support elements (receiving horizontal components from the thrust of the cable system), as well as a stabilizing system that absorbs all temporary loads on the coating, including negative wind pressure . Therefore, the proposed concept for the construction of BSZS takes into account all the conditions necessary for these structures.
So, in order to make the multi-belt cable covering unchangeable under the influence of temporary loads, it is additionally provided, with the help of guy ropes, to add additional load to the covering by the calculated value. At the same time, the covering guys are attached to the foundations of the supporting buildings, which avoids increasing the load on these foundations from the additional weight of the long-span covering caused by the tension of the guys.

As a result of the joint work of the multi-belt cable system and the glazed frame covering located on it, a single, lightweight and reliable long-span translucent cable covering was formed, which today is capable of covering spans of 200-350 meters or more.
It is clear that the roof covering, the basis for which is long-span multi-belt cable systems, can, if desired, be made from any hydro-thermal insulation material, including including translucent. For example, in conditions of low ambient temperatures, the best translucent material today is multi-chamber double-glazed windows.

The advantages of multi-belt cable systems over the currently known technical solutions used to cover large spans are obvious. This is a very significant strength and reliability of such systems, excellent load-bearing capacity, lightness of structures, the ability to cover significantly larger spans, better light transmittance of the coating, several times lower metal consumption of structures and, as a result, relatively low cost of the entire coating.

Application of multi-belt cable systems.

It should be noted that the technology of covering large and extra-large spans using multi-belt cable systems will make it possible to build structures of a wide variety of volumes, shapes and purposes. These can be: the largest hangars and production workshops, indoor athletics and football stadiums, long-span public spaces, entertainment and shopping centers, residential areas under a translucent shell, large glass pyramids and domes (in which a wide variety of multifunctional real estate complexes can be placed or corporate centers). Multi-lane cable systems can also be useful in the construction of new design long-span suspension bridges, especially in places where construction of other types of bridges is impossible or too expensive.

Fig. 12. A translucent structure in the form of a PYRAMID with a height of 200 m.

It seems that the construction of long-span translucent complexes should be developed as block development. And one of the most spectacular and optimal initial options for such a functional development can be, for example, the shape of a translucent block in the form of a regular quadrangular PYRAMID (Fig. 11) with the following parameters:

• height of the pyramid – 200 m;
• base dimensions - 300x300 m;
• base area (territory protected by translucent coatings) – 9.0 ha;
• area of ​​enclosing structures - 150,000 m2;
• the geometric volume of the pyramid (P200) is 6.0 million cubic meters.

In such a glazed quarter, in order not to overcrowd the internal space of the complex, it is reasonable to have only 320-450 thousand square meters of usable space (above ground), occupied by commercial and/or residential real estate and located mainly in the supporting buildings of this translucent complex. The remaining volume of the structure (more than 4.0 million cubic meters) is multifunctional atriums.

For comparison, with an increase in the height of such a pyramid P200 (a geometrically ideal pyramid has a ratio of 3:4:5) by only 50 meters, the parameters of P250 will be: base - 375x375 m; Sbas = 14.1 hectares, Sglass = 235.0 thousand sq.m. There will be an almost twofold increase in the internal volume of the translucent structure, which in this case will be equal to 11.7 million cubic meters, and the amount of space occupied by commercial real estate may increase to 0.8 - 1.0 million square meters. Moreover, what is especially attractive is that the area of ​​the enclosing structures of the P250 pyramid will almost double! less than the total area of ​​the enclosing structures of internal supporting buildings. Specialists should understand the importance of this ratio.
With a further increase in the internal volume of the BSZS and giving it a dome-shaped shape, the decrease in the ratio of the area of ​​the enclosing structures of the translucent complex to the sum of all useful areas of the internal premises (as well as to the sum of the areas of the enclosing structures of internal buildings) will change in a very pleasing progression, i.e. e. the process of such construction will become more and more economically attractive!

Sports centers with translucent coating.
Another promising area for the use of multi-belt cable translucent coverings today seems to be the construction of indoor football stadiums and other long-span sports facilities. Every year the demand for indoor sports stadiums in the world is increasing (for example, not only Europeans and North Americans are building large indoor stadiums for themselves, but also less wealthy countries such as Argentina and Kazakhstan have recently built such structures, and the Philippines is now building, as they say , the largest indoor stadium in the world). In anticipation of preparations for the 2018 football championship, the demand for such facilities may also emerge in Russia.

The uniqueness and high cost of currently existing long-span sports structures (with a span of 120-150 m or more) lies in the fact that each such structure is carried out to the maximum capabilities of the construction industry of the place of its construction, is associated with numerous complex and accurate calculations of load-bearing structures, increased responsibility and significant material intensity of implemented solutions. The disadvantages of the ceilings of all these long-span structures are the same: they are complex, bulky, metal-intensive, and therefore irrational and extremely expensive. In addition, due to the powerful load-bearing metal structures of the coating, the insolation of all indoor stadiums today is extremely low, which makes it very difficult to maintain the natural grass surface of modern sports arenas in good condition.

Fig. 13. Football stadium in Poland. At EURO 2012.
Fig. 14. Wembley Stadium is the most famous stadium in England

It seems that the use of translucent multi-belt cable coverings should radically change this unfavorable state of affairs in the construction of long-span sports facilities (the sketches in Fig. 15-19 show one of the possible options for the construction of a relatively inexpensive indoor multifunctional sports complex).

Rice. 15-18 sketches of a large indoor stadium.
.
1 and 2 – buildings that serve as supporting structures for the translucent coating;
4 – multi-belt cable systems;
10 – guy ropes;
11 – 3-belt cable translucent covering;
18 and 19 – spectator stands;
21 – self-supporting translucent structures

Rice. 19. Section of a 3-belt cable translucent covering (see designation 4 and 11, in Fig. 17)

5 - high-strength metal cable;
6 - cable covering belt;
7 - spacer stand;
8 - horizontal spacer-stretch:
12 - translucent coating elements;
13 - frame structure of the translucent coating.

Multi-belt cable systems (4) (overlapping the span between supports (1 and 2) are inclined outward of the structure due to the difference in the heights of the supporting buildings and are the basis for placing on top of them a sliding translucent covering (11), made of frame structures (13) and translucent elements ( 12) .
The multi-belt cable system, guy ropes (10) and other special technical solutions will provide the cable covering with the necessary rigidity and resistance to the perception of all design loads.
Between the supporting buildings (1 and 2), along the contour of the outer walls of the stadium, self-supporting translucent structures (21) are provided, which make the contour of the outer walls closed.
The use of multi-belt cable coverings will be able to provide all new stadiums with the simplest, most reliable and relatively inexpensive design of a translucent covering, while at the same time providing better insolation of the arena than in all indoor stadiums built to date.

The construction of long-span multi-belt cable-based translucent coverings today is not a very difficult task, since in construction practice there is many years of experience in the use of long-span cable-stayed coverings, which basically use the same technical solutions, materials, products and equipment, and the same technical specialists.

A large and beautiful, indoor and comfortable modern sports center is necessary for every developing city, not only to hold sports competitions in decent conditions throughout the year, but also to widely involve the urban population in active sports and their personal health. To achieve this, a multifunctional sports complex may include not only a high-quality football field, numerous Sport halls, swimming pools and fitness centers, but any choice of facilities for recreational and educational activities various types sports, and the high-rise part of the sports complex, if desired, can accommodate hotel and office centers close to the profile of the facility.

With the help of the best specialized construction companies (for example, the French " Freyssinet International & Cie" or Japanese "TOKYO ROPE MFG.CO, LTD.", which are world leaders in the design and manufacture of cable-stayed structures), it is possible to begin building the proposed long-span translucent objects today.

Fig. 20. Dome-shaped protective structure with a translucent coating.

Prospects for the architecture of long-span translucent complexes.

The huge atrium spaces of the BSZS can combine many tasks. For example, atriums with volumes of millions of cubic meters will be able to accommodate the largest luxury water park, a full-fledged sports stadium, and much more at the same time. But, it seems that in the future, most BSZS will prefer the opportunity to place in their atrium spaces vast and cozy landscaped gardens with sports and children's playgrounds, fountains and waterfalls, enclosures with exotic animals and picturesque ponds, outdoor swimming pools and cafes on the lawns. After all, each such evergreen flowering garden will provide the opportunity for residents and guests of the BSZS to communicate daily with wildlife - both in the hottest summer months, and the long rainy days of autumn, and in the snowy cold months of winter.

Fighters for the conservation of nature should like the fact that during the construction of the BSZS, the process of penetration of living nature inside the huge man-made translucent structures is intensified. By occupying spaces specially prepared for it in the BSZS and forming sustainable ecosystems in them (with the active help of humans), nature will be able to qualitatively fill the architectural objects of the future, making them more functional and more attractive to people. At the same time, in the atrium spaces organized by people, the best BSZS, mutualism (mutually beneficial cohabitation) of nature and man will undoubtedly occur.

Fig.21-22. Atriums of American hotels owned by the famous Gaylord Hotels.

The positive results that will be obtained during the construction of the BSZS fully meet the needs of modern urban planning. This is the economic and environmental attractiveness of the structures; intensive development of the artificial human environment, closely related to the natural environment and ensuring a high quality of life for people; the formation of a new type of eco-cities and improvement of the environmental situation in existing megacities; the emergence of new popular areas for the development of technical progress and significant savings in natural resources.

By many criteria, BSZS best comply with the principles of Green Buildings, and will contribute not only to improving the quality of construction projects, but also to preserving the environment.

Construction of the BSZS will helpdecide the following important tasks of “sustainable development” and the requirements of the “green” standards LEED, BREEAM, DGWB:
- reducing the level of consumption of energy and material resources by buildings;
- reducing adverse impacts on natural ecosystems;
- ensuring a guaranteed level of comfort in the human environment;
- creation of new energy-efficient and energy-saving products, new jobs in the production and maintenance sectors;
- formation of public demand for new knowledge and technologies in the field of renewable energy.

Atriums of translucent structures will certainly return our courtyards to their former relevance and relevance, as a newly created public space that is charming in many respects, freed from cars and filled with sunlight, coziness, and comfort.

The design features of the BSZS and their reasonable use will in the future make it possible to optimize the construction of such structures in such a way that constructing a complex of buildings covered with a translucent dome will be much cheaper than constructing the same complex of buildings under identical conditions, but without a protective dome.
So, it is obvious that the cost of translucent coating and operating costs (with correct and purposeful movement in this direction) will decrease with increasing volume of the structure (not in absolute terms, but relative to costs per 1 square meter of usable area). This natural conclusion is confirmed by ordinary logic, common sense, and mathematics.
And a several-fold reduction in the area of ​​the enclosing structures of the BSZS, relative to the sum of the areas of the enclosing structures of internal buildings, will inevitably lead to a decrease in the energy consumption for heating the BSZS complex and for its air conditioning, relative to the same volume of ordinary buildings not protected by a translucent shell.
At the same time, all internal buildings of the BSZS will have a simplified finishing of external walls (without expensive coatings and lack of insulation), and window openings will not necessarily be glazed with double-glazed windows, which will inevitably affect the cost of the foundations. The main heating and air conditioning systems of interior buildings can be moved into atrium spaces, making interior living and office spaces simpler, more efficient, etc.

New eco-cities in the future, it seems, may well consist mainly of BSZS located close to each other and as autonomous as possible. Such translucent structures will be built among wildlife and integrated into the natural landscape, and will also be connected to each other and to other cities by the most modern high-speed transport communications. This will probably lead not only to a complete abandonment of personal vehicles by many residents of the eco-cities of the future, due to their uselessness, but will also be able to permanently eliminate places where the flow of people and the flow of cars dangerously intersect.

But the most important result of the construction of eco-sustainable, long-span translucent structures is the expansion and improvement of a comfortable human environment, without negative consequences for nature.

Saint Petersburg
06/09/2013

Notes :
. Dome over Houston" - http://youtu.be/vJxJWSmRHyE ;
. The largest tent in the world
- http://yo www.youtube.com/watch utu.be/W3PfL2WY5LM ;
. "Tropical Islands" - www.youtube.com/watch ;
. Masdar City - www.youtube.com/watch;
. Long span suspension bridge -
.

Bibliography :
1. Marcus Vitruvius Pollio, de Architectura - the work of Vitruvius in the English translation of Gwilt (1826);
2. L G. Dmitriev, A. V. Kasilov. "Cable-stayed coverings". Kyiv. 1974;
3. Zverev A.N. Long-span roofing structures for public and industrial buildings. St. Petersburg State University of Civil Engineering - 1998;
4. Kirsanov N.M. Hanging and cable-stayed structures. Stroyizdat - 1981;
5. Smirnov V.A. Suspension bridges of large spans. Higher school. 1970;
6. Eurasian patent No. 016435 - Protective structure with a long-span translucent coating - 2012;
7.

Fig.23-28. Atriums of the American chain of upscale hotels "Gaylord Hotels".

General provisions

Long-span buildings are those in which the distance between the supports (load-bearing structures) of the coverings is more than 40 m.

Such buildings include:

− workshops of heavy engineering factories;

− assembly shops of shipbuilding, machine-building plants, hangars, etc.;

− theaters, exhibition halls, indoor stadiums, train stations, covered parking lots and garages.

1. Features of long-span buildings:

a) large dimensions of buildings in plan, exceeding the radius of action of erection cranes;

b) special methods for installing coating elements;

c) the presence, in some cases, of large parts and structures of the building, whatnots, stands of indoor stadiums, foundations for equipment, bulky equipment, etc. under the covering.

2. Methods for constructing long-span buildings

The following methods are used:

a) open;

b) closed;

c) combined.

2.1. The open method is that first, all the building structures located under the roof are erected, i.e.:

− shelves (single or multi-tiered structure under the roof of industrial buildings for technological equipment, offices, etc.);

− structures for accommodating spectators (in theaters, circuses, indoor stadiums, etc.);

− foundations for equipment;

− sometimes cumbersome technological equipment.

Then the covering is arranged.

2.2. The closed method consists of first removing the covering, and then erecting all the structures underneath it (Fig. 18).

Rice. 18. Scheme of construction of the gym (cross section):

1 – vertical load-bearing elements; 2 – membrane coating; 3 – built-in premises with stands; 4 – mobile jib crane

2.3. The combined method consists of first performing all the structures located below the covering in separate sections (grips), and then constructing the covering (Fig. 19).

Rice. 19. Fragment of the construction plan:

1 – installed building covering; 2 – shelf; 3 – foundations for equipment; 4 – crane tracks; 5 – tower crane

The use of methods for constructing large-span buildings depends on the following main factors:

− on the possibility of locating load-lifting cranes in plan in relation to the building under construction (outside the building or in plan);

− on the availability and possibility of using crane beams (overhead cranes) for the construction of internal parts of building structures;

− on the possibility of installing coatings in the presence of completed parts of the building and structures located under the coating.

When constructing long-span buildings, a particular difficulty is the installation of coverings (shells, arched, domed, cable-stayed, membrane).

The technology for constructing the remaining structural elements is usually not difficult. The work on their installation is discussed in the course “Technology of Construction Processes”.

It is considered in the course of TSP and will not be considered in the course of TVZ and C and the technology of beam coverings.

3.1.3.1. TVZ in the form of shells

In recent years, a large number of thin-walled spatial reinforced concrete covering structures in the form of shells, folds, tents, etc. have been developed and implemented. The effectiveness of such structures is due to more economical consumption of materials, lighter weight and new architectural qualities. Already the first experience in operating such structures made it possible to discover two main advantages of spatial thin-walled reinforced concrete pavements:

− cost-effectiveness resulting from a more complete use of the properties of concrete and steel compared to planar systems;

− the possibility of rational use of reinforced concrete to cover large areas without intermediate supports.

Reinforced concrete shells, according to the method of construction, are divided into monolithic, assembly-monolithic and prefabricated. Monolithic shells entirely concreted at the construction site on stationary or mobile formwork. Prefabricated monolithic shells can consist of prefabricated contour elements and a monolithic shell, concreted on movable formwork, most often suspended from mounted diaphragms or side elements. Prefabricated shells assembled from separate, pre-fabricated elements, which, after installing them in place, are joined together; Moreover, the connections must ensure reliable transfer of forces from one element to another and the operation of the prefabricated structure as a single spatial system.

Prefabricated shells can be divided into the following elements: flat and curved slabs (smooth or ribbed); diaphragms and side elements.

Diaphragms and side elements can be either reinforced concrete or steel. It should be noted that the choice of design solutions for shells is closely related to construction methods.

Double shell(positive Gaussian) curvature, square in plan, formed from prefabricated reinforced concrete ribbed shells And contour trusses. The geometric shape of double-curvature shells creates favorable conditions for static work, since 80% of the shell area works only in compression and only in the corner zones are there tensile forces. The shell of the shell has the shape of a polyhedron with diamond-shaped edges. Since the slabs are flat and square, the diamond-shaped edges are achieved by sealing the seams between them. Average standard slabs are molded with dimensions of 2970×2970 mm, thicknesses of 25, 30 and 40 mm, with diagonal ribs 200 mm high, and side ribs 80 mm high. The contour and corner slabs have diagonal and side ribs of the same height as the middle ones, and the side ribs adjacent to the edge of the shell have thickenings and grooves for the outlets of the contour truss reinforcement. The connection of the slabs to each other is carried out by welding the frame releases of the diagonal ribs and cementing the seams between the slabs. A triangular cutout is left in the corner slabs, which is sealed with concrete.

The contour elements of the shell are made in the form of solid trusses or prestressed diagonal half-trusses, the joint of which in the upper chord is made by welding overlays, and in the lower - by welding the outlets of the rod reinforcement with their subsequent concrete coating. It is advisable to use shells to cover large areas without intermediate supports. Reinforced concrete shells, which can be given virtually any shape, can enrich the architectural design of both public and industrial buildings.

Rice. 20. Geometric schemes of shells:

A– cutting with planes parallel to the contour; b– radial-circular cutting; V– cutting into diamond-shaped flat slabs

In Fig. Figure 21 shows geometric schemes for covering buildings with a rectangular grid of columns with shells made of cylindrical panels.

Depending on the type of shell, the size of its elements, as well as the dimensions of the shell in plan, installation is carried out using various methods, differing mainly in the presence or absence of mounting scaffolding.

Rice. 21. Options for the formation of prefabricated cylindrical shells:

A– from curved ribbed panels with side elements; b– the same with one side element; V– from flat ribbed or smooth slabs, side beams and diaphragms; G– from large curved panels, side beams and diaphragms; d– of arches or trusses and vaulted or flat ribbed panels (short shell)

Let's consider an example of the construction of a two-span building with a covering of eight square-plan shells of doubly positive Gaussian curvature. The dimensions of the coating structural elements are shown in Fig. 22, A. The building has two spans, each of which contains four cells measuring 36 × 36 m (Fig. 22, b).

The significant consumption of metal for supporting scaffolding during the installation of double-curvature shells reduces the efficiency of using these progressive structures. Therefore, for the construction of such shells up to 36 × 36 m in size, rolling telescopic conductors with mesh circles are used (Fig. 22, V).

The building in question is a homogeneous object. Installation of coating shells includes the following processes: 1) installation (rearrangement) of the conductor; 2) installation of contour trusses and panels (installation, laying, alignment, welding of embedded parts); 3) monolithization of the shell (filling of seams).

Rice. 22. Construction of a building covered with prefabricated shells:

A– design of the coating shell; b– diagram of the division of the building into sections; V– diagram of the conductor’s operation; G– the sequence of installation of covering elements for one area; d– the sequence of construction of the covering in sections of the building; I–II – numbers of spans; 1 – contour shell trusses, consisting of two half-trusses; 2 – covering slab measuring 3×3 m; 3 – building columns; 4 – telescopic conductor towers; 5 – mesh conductor circles; 6 – hinged supports of the conductor for temporary fastening of elements of contour trusses; 7 – 17 – sequence of installation of contour trusses and covering slabs.

Since when installing the coating, a rolling conductor is used, which is moved only after curing the mortar and concrete, one span cell is taken as the installation section (Fig. 22, b).

Installation of the shell panels begins with the outer ones, based on the conductor and the contour truss, then the remaining shell panels are mounted (Fig. 22, G, d).

3.1.3.2. Technology for constructing buildings with domed roofs

Depending on the design solution, the installation of domes is carried out using a temporary support, a hinged method or in its entirety.

Spherical domes are erected in ring tiers from prefabricated reinforced concrete panels in a mounted way. Each of the ring tiers, after complete assembly, has static stability and load-bearing capacity and serves as the basis for the overlying tier. Prefabricated reinforced concrete domes of indoor markets are installed in this way.

The panels are lifted by a tower crane located in the center of the building. Temporary fastening of the panels of each tier is carried out using an inventory device (Fig. 23, b) in the form of a stand with guys and a turnbuckle. The number of such devices depends on the number of panels in the ring of each tier.

Work is carried out from inventory scaffolding (Fig. 23, V), arranged outside the dome and moved during installation. Adjacent panels are connected to each other with bolts. The seams between the panels are sealed with cement mortar, which is first laid along the edges of the seam and then pumped into its internal cavity using a mortar pump. A reinforced concrete belt is placed along the upper edge of the panels of the assembled ring. After the mortar of the seams and the concrete of the belt acquire the required strength, the racks with guys are removed, and the installation cycle is repeated on the next tier.

Prefabricated domes are also mounted in a hinged manner by sequential assembly of ring belts using a movable metal truss template and racks with hangers for holding prefabricated slabs (Fig. 23, G). This method is used when installing prefabricated reinforced concrete circus domes.

To install the dome, a tower crane is installed in the center of the building. A mobile template truss is installed on the crane tower and the ring track located along the reinforced concrete cornice of the building. To ensure greater rigidity, the crane tower is braced with four braces. If the boom reach and lifting capacity of one crane are insufficient, a second crane is installed on the ring track near the building.

Prefabricated dome panels are installed in the following order. Each panel, in an inclined position corresponding to its design position in the coating, is lifted by a tower crane and installed with its lower corners on the inclined welded linings of the assembly, and with its upper corners on the installation screws of the template truss.

Rice. 23. Construction of buildings with domed coverings:

A– dome design; b– diagram of temporary fastening of dome panels; V– diagram of fastening the scaffolding for the construction of the dome; G– diagram of the dome installation using a mobile template truss; 1 – lower support ring; 2 – panels; 3 – upper support ring; 4 – rack of inventory device; 5 – guy; 6 – turnbuckle; 7 – mounted panel; 8 – mounted panels; 9 – strut with holes to change the slope of the scaffold bracket; 10 – rack for railings; 11 – bracket crossbar; 12 – eye for attaching the bracket to the panel; 13 – mounting racks; 14 – strut braces; 15 – hangers for holding slabs; 16 – template truss; 17 – crane braces; 18 – panel truck

Next, the upper edges of the embedded parts of the upper corners of the panel are aligned, after which the slings are removed, the panel is secured with hangers to the mounting posts, and the hangers are tensioned using turnbuckles. The template truss set screws are then lowered by 100 - 150 mm and the template truss is moved to a new position for installation of the adjacent panel. After installing all the belt panels and welding the joints, the joints are sealed with concrete.

The next dome belt is installed after the concrete joints of the underlying belt have acquired the required strength. Upon completion of installation of the upper belt, remove the pendants from the panels of the underlying belt.

In construction, they also use the method of lifting concrete floors with a diameter of 62 m in their entirety using a system of jacks mounted on columns.

3.1.3.3. Technology for constructing buildings with cable-stayed roofs

The most critical process in the construction of such buildings is the installation of coverings. The composition and sequence of installation of cable-stayed coverings depends on their design diagram. The leading and most complex process in this case is the installation of the cable-stayed network.

The structure of the suspended roof with a cable system consists of a monolithic reinforced concrete support contour; fixed on the supporting contour of the cable-stayed network; prefabricated reinforced concrete slabs laid on a cable-stayed network.

After the design tension of the cable-stayed network and grouting of the seams between the slabs and cables, the shell works as a single monolithic structure.

The cable network consists of a system of longitudinal and transverse cables located along the main directions of the shell surface at right angles to each other. In the support contour, the cables are secured using anchors consisting of sleeves and wedges, with the help of which the ends of each cable are crimped.

The cable-stayed shell network is installed in the following sequence. Each cable is installed in place using a crane in two steps. First, with the help of a crane, one end of it, removed from the drum by a traverse, is fed to the installation site. The cable anchor is pulled through the embedded part in the support contour, then the remaining part of the cable on the drum is secured and rolled out. After this, two cranes are used to lift the cable to the level of the support contour, while simultaneously pulling the second anchor to the support contour with a winch (Fig. 24, A). The anchor is pulled through the embedded part in the support contour and secured with a nut and washer. The cables are lifted together with special hangers and control weights for subsequent geodetic alignment.

Rice. 24. Construction of a building with cable-stayed roofing:

A– diagram of lifting the working cable; b– diagram of mutually perpendicular symmetrical tension of cables; V– alignment diagram of longitudinal cables; G– details of the final fastening of the cables; 1 – electric winch; 2 – guy; 3 – monolithic reinforced concrete support contour; 4 – lifted cable; 5 – traverse; 6 – level

Upon completion of the installation of the longitudinal cables and their pre-tensioning to a force of 29.420 - 49.033 kN (3 - 5 tf), a geodetic verification of their position is performed by determining the coordinates of the points of the cable network. Tables are drawn up in advance in which, for each cable, the distance of the control weight attachment points on the anchor sleeve from the reference point is indicated. At these points, test weights weighing 500 kg are suspended from a wire. The lengths of the pendants are different and calculated in advance.

When the working cables sag correctly, the control weights (risks on them) should be at the same mark.

After adjusting the position of the longitudinal cables, the transverse cables are installed. The places where they intersect with the working cables are secured with constant compression. At the same time, temporary guy wires are installed to secure the position of the cable-stay intersection points. Then the cable network surface is re-checked for compliance with the design. The cable-stayed network is then tensioned in three stages using 100-ton hydraulic jacks and traverses attached to sleeve anchors.

The tension sequence is determined from the conditions of tension of the cables in groups, simultaneous tension of the groups in the perpendicular direction, and symmetry of the tension of the groups relative to the axis of the building.

At the end of the second stage of tension, i.e. When the forces determined by the project are achieved, prefabricated reinforced concrete slabs are laid on the cable-stayed network in the direction from the lower mark to the upper one. In this case, formwork is installed on the slabs before they are lifted to seal the seams.

3.1.3.4. Technology of construction of buildings with membrane coatings

TO metal hanging coatings include thin-sheet membranes that combine load-bearing and enclosing functions.

The advantages of membrane coatings are their high manufacturability and installation, as well as the nature of the coating’s operation in biaxial tension, which makes it possible to cover 200-meter spans with a steel membrane only 2 mm thick.

Hanging tensile elements are usually secured to rigid supporting structures, which can be in the form of a closed contour (ring, oval, rectangle) resting on columns.

Let's consider the technology of installing a membrane coating using the example of the coating of the Olimpiysky sports complex in Moscow.

Sports complex"Olympic" is designed as a spatial structure of an elliptical shape 183×224 m. Along the outer contour of the ellipse, with a step of 20 m, there are 32 steel lattice columns, rigidly connected to the outer support ring (section 5×1.75 m). A membrane covering is suspended from the outer ring - a shell with a sag of 12 m. The covering has 64 stabilizing trusses, 2.5 m high, radially located with a step along the outer contour of 10 m, connected by ring elements - girders. The membrane petals were fastened to each other and to the radial elements of the “bed” with high-strength bolts. In the center, the membrane is closed by an internal metal ring of an elliptical shape measuring 24x30 m. The membrane covering was attached to the outer and inner rings with high-strength bolts and welding.

The installation of the membrane covering elements was carried out in large spatial blocks using a BK-1000 tower crane and two installation beams (with a lifting capacity of 50 tons), moving along the outer support ring. Along the long axis, two blocks were assembled simultaneously on two stands.

All 64 stabilizing coating trusses were united in pairs into 32 blocks of nine standard sizes. One such block consisted of two radial stabilizing trusses, girders along the upper and lower chords, vertical and horizontal connections. Pipelines for ventilation and air conditioning systems were installed in the unit. The mass of assembled stabilizing truss blocks reached 43 tons.

The covering blocks were lifted using a spreader beam, which absorbed the thrust force from the stabilizing trusses (Fig. 25).

Before lifting the truss blocks, they pre-stressed the upper chord of each truss with a force of about 1300 kN (210 MPa) and secured them with this force to the support rings of the coating.

The installation of prestressed blocks was carried out in stages by symmetrically installing several blocks along radii of the same diameter. After the installation of eight symmetrically installed blocks along with traverse spacers, they were simultaneously untwisted with the transmission of thrust forces evenly to the outer and inner rings.

The block of stabilizing trusses was lifted using a BK-1000 crane and an installer approximately 1 m above the outer ring. Then the chevre was moved to the installation site of this block. The block was unslinged only after it had been fully secured to the inner and outer rings as designed.

The membrane shell weighing 1569 tons consisted of 64 sector petals. The membrane petals were installed after the installation of the stabilization system was completed and secured with high-strength bolts with a diameter of 24 mm.

The membrane panels arrived at the installation site in the form of rolls. Rolling racks were located at the site where the stabilizing trusses were assembled.

Rice. 25. Scheme of installation of coating with enlarged blocks:

A– plan; b- incision; 1 – chevre-installer; 2 – stand for larger assembly of blocks; 3 – traverse-spacer for lifting the block and prestressing the upper chords of the trusses using a lever device (5); 4 – enlarged block; 6 – installation crane BK – 1000; 7 – central support ring; 8 – central temporary support; I – V – sequence of installation of blocks and dismantling of traverse struts

The installation of the petals was carried out in the sequence of installation of the stabilizing trusses. The tension of the membrane petals was carried out by two hydraulic jacks with a force of 250 kN each.

In parallel with laying and tensioning the membrane petals, holes were drilled and high-strength bolts were installed (97 thousand holes with a diameter of 27 mm). After assembly and design fastening of all elements of the coating, it was untwisted, i.e. release of the central support and smooth inclusion of the entire spatial structure into operation.